Multi-component copolymer rubber, a process for producing the same and a rubber composition containing the multi-component copolymer rubber

ABSTRACT

A multi-component copolymer rubber consisting essentially of (A) 20 to 69.5% by weight of a cyano-substituted alkyl (meth)acrylate, (B) 30 to 79.5% by weight of an alkyl acrylate, (C) 0.5 to 10% by weight of a crosslinkable monomer and (D) 0 to 10% by weight of other ethylenically unsaturated monomer copolymerizable with (A), (B) and (C), excels in heat resistance, ozone resistance, sour gasoline resistance and sour gasohol resistance. There properties of said multi-component copolymer rubber can further be improved by incorporating into the copolymer rubber a crosslinking agent, a metal salt, a vinylidene fluoride polymer, a vinyl chloride resin or other multi-component copolymer rubber.

This is a continuation of Application Ser. No. 716,350, filed Mar. 26, 1985, now U.S. Pat. No. 4,625,005.

This invention relates to a novel multi-component copolymer rubber consisting essentially of a cyano-substituted alkyl (meth)acrylate, an alkyl acrylate and a diene monomer, excellent in heat resistance, ozone resistance, sour gasoline resistance and sour gasohol resistance, as well as to a rubber composition containing said multi-component copolymer rubber and other components.

In recent years, in automobiles, gasoline-resistant rubbers are in use in atmospheres whose temperatures are becoming increasingly higher in connection with countermeasures for exhaust gas regulations and engine modifications for higher performance. Hence, there is now required a gasoline-resistant rubber excellent in heat resistance and ozone resistance. With respect to these gasoline-resistant rubbers, there is a further problem that gasolines are oxidized in fuel systems of automobiles, etc. to produce a sour gasoline [the sour gasoline refers to a gasoline containing peroxides produced by gasoline oxidation at high temperatures and it is described in detail in A. Nersasian, Rubber and Plastics News, June 26 (1978)] and this sour gasoline deteriorates gasoline-resistant rubbers.

In connection with tight supply of crudes on worldwide basis, addition of an alcohol to a gasoline has been tried. This gasoline-alcohol mixture, namely, gasohol is also oxidized to produce a sour gasohol and this sour gasohol deteriorates gasoline-resistant rubbers as well.

As gasoline-resistant rubbers, butadiene-acrylonitrile rubber has widely been used in such applications as hoses, gaskets, O-rings, packings and oil seals. However, butadiene-acrylonitrile rubber is poor in ozone resistance and insufficient in heat resistance and sour gasoline resistance, and therefore, it is difficult to provide a rubber part having a sufficient reliability even when used in contact with a gasoline at high temperatures as mentioned above.

In order to overcome the drawbacks of butadiene-acrylonitrile rubber, it is known to use a blend of butadiene-acrylonitrile rubber with poly(vinyl chloride), thereby improving sour gasoline resistance and ozone resistance [Japanese Patent Application Kokai (Laid-Open) No. 89,388/80]. However, this blend has no improved heat resistance, is poor in other properties such as low-temperature resistance and permanent compression set, which are required as gasoline-resistant rubber materials and cannot be said to have sufficient gasohol resistance. Hence, it has been desired to overcome these drawbacks. Fluororubber has been spotlighted as a gasoline-resistant rubber material because of its excellency in sour gasoline resistance, ozone resistance and heat resistance. However, the fluororubber has an insufficient flexibility at low temperatures, and poor physical properties, and is difficult to handle and very expensive. Accordingly it cannot be used as a general purpose gasoline resistant rubber.

Under such circumstances, the present inventors have studied on various materials which are excellent in heat resistance, ozone resistance, sour gasoline resistance and sour gasohol resistance and which can easily be used as a gasoline-resistant and gasohol-resistant material using conventional molding equipments and techniques. As a result, it has been found that the above requirements can be met by a novel multi-component copolymer consisting essentially of a cyano-substituted alkyl (meth)acrylate, an alkyl acrylate and a crosslinkable monomer and also by a composition of said multi-component copolymer and other components.

According to this invention, there is provided a multi-component copolymer rubber consisting essentially of

(A) 20 to 69.5% by weight of a cyano-substituted alkyl (meth)acrylate,

(B) 30 to 79.5% by weight of an alkyl acrylate,

(C) 0.5 to 10% by weight of a crosslinkable monomer, and

(D) 0 to 10% by weight of other ethylenically unsaturated monomer copolymerizable with the components (A), (B) and (C).

This invention further provides a process for producing said copolymer rubber, a composition of said copolymer rubber and other components, and uses of said copolymer rubber and said composition.

The cyano-substituted alkyl (meth)acrylate which is the component (A) of the multi-component copolymer rubber of this invention is represented by the formula (I): ##STR1## wherein R¹ is a hydrogen atom or a methyl group and R² is an alkylene group. In the formula (I), --R² --CN is a cyanoalkyl group of 2 to 12 carbon atoms. Specific examples of the cyano-substituted alkyl (meth)acrylate are cyanomethyl (meth)acrylate, 1-cyanoethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, 1-cyanopropyl (meth)acrylate, 2-cyanopropyl (meth)acrylate, 3-cyanopropyl (meth)acrylate, 4-cyanobutyl (meth)acrylate, 6-cyanohexyl (meth)acrylate, 2-ethyl-6-cyanohexyl (meth)acrylate, 8-cyanooctyl (meth)acrylate, etc. Of these, preferred are 2-cyanoethyl acrylate, 3-cyanopropyl acrylate and 4-cyanobutyl acrylate. Particularly, 2-cyanoethyl acrylate is preferred.

The alkyl acrylate which is the component (B) is represented by the formula (II): ##STR2## wherein R³ is an alkyl group having 1 to 18 carbon atoms. Specific examples of the alkyl acrylate are methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-methylpentyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-decyl acrylate, n-dodecyl acrylate, n-octadecyl acrylate, etc. Of these, preferred are ethyl acrylate, propyl acrylate, n-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate and n-octyl acrylate. Particularly, ethyl acrylate and n-butyl acrylate are preferred.

As the crosslinkable monomer which is the component (C), there can be used (C-I) a diene compound, (C-II) a (meth)acrylic acid ester containing a dihydrodicyclopentadienyl group, (C-III) an epoxy group-containing, ethylenically unsaturated compound, (C-IV) an active halogen-containing, ethylenically unsaturated compound, (C-V) an active hydrogen-containing monomer and (C-VI) a carboxyl group-containing monomer.

The diene compound (C-I) includes non-conjugated dienes such as alkylidenenorbornenes, alkenylnorbornenes, dicyclopentadiene, methylcyclopentadiene and dimers thereof as well as conjugated dienes such as butadiene and isoprene. Of these, non-conjugated dienes are preferred, and alkylidenenorbornenes are particularly preferred. Of the alkylidenenorbornenes, ethylidenenorbornene is most preferable.

(meth)acrylic acid ester containing a dihydrodicyclopentadienyl group (C-II) includes dihydrodicyclopentadienyl (meth)acrylate, dihydrodicyclopentadienyl oxyethyl (meth)acrylate and the like.

The epoxy group-containing, ethylenically unsaturated monomer (C-III) includes allyl glycidyl ether, vinyl glycidyl ether, 2-methyl-1-propenyl glycidyl ether, glycidyl methacrylate and glycidyl acrylate. Of these, allyl glycidyl ether, glycidyl methacrylate and glycidyl acrylate are preferred. Allyl glycidyl ether is most preferable.

The active halogen-containing, ethylenically unsaturated compound (C-IV) includes vinylbenzyl chloride, vinylbenzyl bromide, 2-chloroethyl vinyl ether, vinyl chloroacetate, ethylene chloroacetate methacrylate, vinyl chloropropionate, allyl chloroacetate, allyl chloropropionate, 2-chloroethyl acrylate, 2-chloroethyl methacrylate, 2-hydroxypropylene chloroacetate methacrylate, chloromethyl vinyl ketone, 2-chloroacetoxymethyl-5-norbornene, norbornylmethyl chloroacetate, 4-chloromethylstyrene, vinyl chloride, vinylidene chloride, etc. Of these, preferred are vinyl chloroacetate, allyl chloroacetate, 2-chloroethyl vinyl ether, vinylbenzyl chloride, 2-chloroethyl methacrylate and 2-chloroethyl acrylate.

The active hydrogen-containing monomer (C-V) includes allyl cyanoacetate, etc.

The carboxyl group-containing monomer includes acrylic acid, methacrylic acid, crotonic acid, 2-pentenoic acid, maleic acid, fumaric acid, itaconic acid, etc.

The other ethylenically unsaturated monomer which is the component (D) is an optional component. It includes methacrylates such as methyl methacrylate, octyl methacrylate and the like; alkoxyalkyl acrylates such as methoxyethyl acrylate, butoxyethyl acrylate and the like; alkyl vinyl ketones such as methyl vinyl ketone and the like; vinyl ethers and allyl ethers such as vinyl ethyl ether, allyl methyl ether and the like; vinyl aromatic compounds such as styrene, α-methylstyrene, chlorostyrene, vinyltoluene and the like; alkenylnitriles such as acrylonitrile, methacrylonitrile and the like; alkenylamides such as acrylamide, methacrylamide, N-methylolacrylamide and the lke; and alkyl fumarates.

The proportions of the components (A), (B), (C) and (D) in the copolymer rubber of this invention are 20 to 69.5%, preferably 25 to 60%, by weight of the component (A), 30 to 79.5%, preferably 35 to 75%, by weight of the component (B), 0.5 to 10%, preferably 0.5 to 5%, by weight of the component (C) and 0 to 10%, preferably 0 to 7%, by weight of the component (D).

When the component (A) is less than 20% by weight, the copolymer rubber is poor in gasoline resistance and sour gasoline resistance. When the component (A) exceeds 69.5% by weight, the copolymer rubber is poor in physical properties such as tensile strength and elongation.

When the component (B) is less than 30% by weight, the multi-component copolymer rubber is poor in physical properties. When the component (B) exceeds 79.5% by weight, the multi-component copolymer rubber is deteriorated in gasoline resistance and sour gasoline resistance.

When the component (C) is less than 0.5% by weight, the multi-component copolymer rubber requires a long time for crosslinking and has no sufficient tensile strength as possessed by crosslinked rubbers. When the component (C) exceeds 10% by weight, the multi-component copolymer rubber becomes hard and has a reduced elongation.

The glass transition temperature of the multi-component copolymer rubber of this invention is preferably a glass transition temperature of -10° C. or less.

The multi-component copolymer rubber of this invention can easily be produced by subjecting to radical polymerization a mixture consisting of (A) 15 to 70% by weight of a cyano-substituted alkyl (meth)acrylate, (B) 30 to 84.5% by weight of an alkyl acrylate, (C) 0.5 to 15% by weight of a crosslinkable monomer and (D) 0 to 15% by weight of an ethylenically unsaturated monomer copolymerizable with (A), (B) and (C). This radical polymerization can be conducted by a conventional polymerization method such as bulk polymerization, solution polymerization, emulsion polymerization or suspension polymerization, wherein the monomers and other components are added at one time, continuously or intermittently.

The radical polymerization initiator used in the above polymerization may be conventional free radical catalysts such as peroxides, redox catalysts, persulfates and azo compounds. The polymerization can be conducted at a temperature ranging from 0° C. to 80° C., preferably 5° C. to 60° C.

The multi-component rubber obtained by the above polymerization can be recovered by a conventional coagulation method using a metal salt such as calcium chloride or the like or using a non-solvent such as ethanol, methanol or the like.

The form of the multi-component copolymer rubber of this invention is not critical, and the multi-component copolymer rubber can be produced in a solid form or in a liquid form depending upon the uses. The molecular weight of the multi-component copolymer rubber is not critical; however, when used in a solid form, the multi-component copolymer rubber has preferably a Mooney viscosity (ML₁₊₄, 100° C.) of 20 to 150, more preferably 25 to 100.

Into the multi-component copolymer rubber of this invention can optionally be incorporated conventional compounding agents such as a crosslinking agent, a crosslinking accelerator, a reinforcing agent, a filler, a plasticizer, a softener, an aging inhibitor, a stabilizer, a foaming agent and the like. The resulting compound can be subjected to crosslinking by a conventional method to easily obtain a crosslinked product.

As the above crosslinking agent, an appropriate compound may be selected depending upon the type of the functional group to be used in the formation of crosslinkage of the copolymer. For example, when a diene compound or a (meth)acrylic acid ester containing a dihydrodicyclopentadienyl group is introduced into the copolymer by copolymerization to form carbon-carbon double bonds in the copolymer, there can preferably be used conventional crosslinking agents which are employed for diene type rubbers (styrene-butadiene rubber, isoprene rubber, butadiene-acrylonitrile rubber, etc.), such as vulcanizing agents (e.g. sulfur, thiuram compound) and organic peroxides. When an epoxy group-containing monomer is introduced, the crosslinking agents may be ammonium compounds, polyamines, polyamine salts, a combination of a polyamine with sulfur or dibenzothiazyl disulfide, dithiocarbamic acid salts, a combination of sulfur with a metal salt of a fatty acid, a combination of sulfur with a metal salt of a fatty acid and a maleimide, thiourea derivatives, and a combination of a thiourea derivative with red lead or dibasic lead phosphite. When an active halogen-containing, ethylenically unsaturated compound is used, the crosslinking agents may be polyamines, polyamine salts, a combination of a polyamine with sulfur or dibenzothiazyl disulfide, ammonium compounds, a combination of a metal salt of a fatty acid with sulfur, a combination of a metal salt of a fatty acid with sulfur and a maleimide, thiourea derivatives, and a combination of a thiourea derivative and red lead or dibasic lead phosphite. When an active hydrogen-containing monomer is used, the crosslinking agents may be tetramethylthiuram disulfide or tetraethylthiuram disulfide. When a carboxyl group-containing monomer is used, the crosslinking agents may be zinc oxide or lead oxide. When the ammonium compounds are used as the crosslinking agent, they may be, for example, ammonium benzoate or ammonium adipate. When the polyamines are used, they may be, for example, triethylenetetramine, hexamethylenetetramine or triethyltrimethylenetriamine. An example of the polyamine salts is hexamethylenediamine carbamate. Examples of the dithiocarbamic acid salts are zinc dimethyldithiocarbamate and iron dimethyldithiocarbamate. Examples of the metal salts of fatty acids are sodium myristate, sodium palmitate, sodium stearate, sodium arachate, sodium behenate and their corresponding potassium salts. Examples of the thiourea derivatives are 2-mercaptoimidazoline and N,N'-diethylthiourea. An example of the maleimides is N,N'-m-phenylenebismaleimide.

The amount of the crosslinking agent used in this invention is not critical and may be varied appropriately depending upon the type and amount of crosslinkable monomer used and also depending upon the type of crosslinking agent used. For example, an ammonium compound is used in an amount of 0.1 to 5 parts by weight; a polyamine or a polyamine salt used in an amount of 0.1 to 5 parts by weight; sulfur used in an amount of 0.1 to 2 parts by weight; a dithiocarbamic acid salt used in an amount of 0.1 to 10 parts by weight; a metal salt of a fatty acid used in an amount of 0.1 to 10 parts by weight; and a thiourea derivative used in an amount of 0.1 to 5 parts by weight.

The crosslinked product of a vulcanizable rubber composition containing the multi-component copolymer rubber of this invention and a crosslinking agent excels in gasoline resistance, sour gasoline resistance, heat resistance and ozone resistance and has good low-temperature resistance, tensile strength and elongation, and has a small permanent compression set. Therefore, it can be used in fuel system hoses of automobiles; other hoses, diaphragms and sealing materials (e.g. gasket, O-ring, oil seal) which come in contact with fuels, hydraulic oils, lubricating oils, etc.; rolls, transfer belts and conveyor belts requiring oil resistance and solvent resistance which are used in iron manufacure, spinning, printing, paper making, dyeing, etc.; and so forth. Being excellent particularly in sour gasoline resistance, the vulcanizable rubber composition can preferably be used as a rubber for fuel system hoses of automobiles.

A rubber compound obtained by optionally incorporating into the multi-component copolymer rubber of this invention, conventional compounding chemicals such as a reinforcing agent, a filler, a plasticizer, a softener, a crosslinking agent, a stabilizer and the like and further optionally incorporating polymers such as PVC, acrylic rubber, NBR, fluororubber, epichlorohydrin rubber and the like, is excellent in gasoline resistance, sour gasoline resistance, ozone resistance and heat resistance and further good in tensile strength, elongation and low-temperature resistance. Therefore, the rubber compound provides a very excellent material for use in inner tubes of fuel system rubber hoses of automobiles, particularly for use in inner tubes of rubber hoses connecting metal pipes in automobile engines.

In this invention, a mixture consisting of (A) a cyano-substituted alkyl (meth)acrylate, (B) an alkyl acrylate, (C) a crosslinkable monomer and (D) other ethylenically unsaturated monomer is emulsion-polymerized at 0° C. to 80° C. in the presence of a radical polymerization catalyst, and to the resulting polymerization mixture is added a metal salt or a combination of an inorganic acid and a metal salt to coagulate a copolymer rubber, after which a releasing agent is added to the copolymer rubber coagulated, to obtain a multi-component copolymer rubber composition which has good kneadability, excellent heat resistance, ozone resistance and sour gasoline resistance and good tensile strength and elongation.

The metal salt may be calcium chloride, magnesium sulfate or the like. The inorganic acid may be sulfuric acid, or the like.

The releasing agent may be hydrocarbon compound such as paraffin wax or the like; a fatty acid compound such as stearic acid or the like; a fatty acid amide compound; a fatty acid ester compound; a phosphoric acid ester compound; or a metal salt of a fatty acid. Of these, preferred are metal salts of fatty acids, phosphoric acid ester compounds and fatty acid ester compounds. Metal salts of fatty acids are more preferable in view of the good kneadability of the rubber composition obtained, and the addition of the metal salt does not result in any deterioration of the physical properties of the vulcanizate.

The amount of the releasing agent used is preferably 0.5 to 10 parts by weight per 100 parts by weight of the rubber. When the amount is less than 0.5 part by weight, the kneadability of the rubber composition obtained is not improved. When the amount exceeds 10 parts by weight, the physical properties of a vulcanizate of the rubber composition obtained are greatly deteriorated.

The releasing agent can be added mechanically by a conventional molding equipment such as a roll, a Banbury mixer, a kneader or the like. Alternatively, it can be added in the form of an emulsion.

Addition of a plasticizer is preferred for improvement of the low-temperature resistance. The plasticizer may be a phthalic acid derivative compound such as diethyl phthalate, di-(2-ethylhexyl)phthalate, dibutyl phthalate, di-n-octyl phthalate, dimethylcyclohexyl phthalate or the like; an isophthalic acid derivative compound such as diisooctyl isophthalate or the like; a tetrahydrophthalic acid derivative compound such as di-(2-ethylhexyl) tetrahydrophthalate or the like; an adipic acid derivative compound such as di-(2-ethylhexyl)adipate, di-(butoxyethoxyethyl)adipate, butyldiglycol adipate or the like; an azelaic acid derivative compound such as di-(2-ethylhexyl)azelate or the like; a sebacic acid derivative compound such as di-(2-ethylhexyl)sebacate, di-n-butyl sebacate or the like; a fatty acid derivative compound such as diethylene glycol monolaurate or the like; a phosphoric acid derivative compound such as tri(2-ethylhexyl)phosphate, triphenyl phosphate or the like; a glycol derivative compound such as dibutyl methylenebisthioglycolate or the like; a glycerine derivative compound; an epoxy derivative compound; or a polymeric plasticizer such as a polyester compound, a polyether compound, a polyetherester compound or the like. Of these, preferred are polymeric plasticizers having a molecular weight of 300 to 3,000 such as polyester compounds, polyether compounds and polyetherester compounds.

The plasticizer is added in an amount of 2 to 15 parts by weight per 100 parts by weight of the rubber. When it is used in an amount of less than 2 parts by weight, no sufficient improvement in low-temperature resistance is obtained. When the plasticizer is added in an amount of more than 15 parts by weight, reduction in tensile strength becomes large.

By further incorporating into the multi-component copolymer rubber of this invention a vinylidene fluoride polymer, a vinyl chloride resin, a nitrile rubber or a partially hydrogenated product thereof, or an acrylic rubber, a rubber composition can be produced which is excellent not only in gasoline resistance, gasohol resistance, sour gasoline resistance and sour gasohol resistance but also in ozone resistance, heat resistance and low-temperature resistance.

In this case, the multi-component copolymer rubber may consist essentially of

(A) 10 to 69.5% by weight of a cyano-substituted alkyl (meth)acrylate,

(B) 30 to 89.5% by weight of an alkyl acrylate,

(C) 0.5 to 10% by weight of a crosslinkable monomer, and

(D) 0 to 10% by weight of other ethylenically unsaturated monomer copolymerizable with the components (A), (B) and (C).

The vinylidene fluoride polymer mentioned above includes a poly(vinylidene fluoride) as well as copolymers between vinylidene fluoride and ethylene trifluoride, propylene pentafluoride, propylene hexafluoride, vinyl acetate, ethylene, propylene, butadiene, styrene, an acrylic acid ester or the like wherein the content of vinylidene fluoride is usually at least 40 mole %, preferably at least 60 mole %. The degree of polymerization of the vinylidene fluoride polymer is not critical but is preferably 100 to 100,000.

The vinyl chloride resin mentioned above includes a poly(vinyl chloride) as well as copolymers between vinyl chloride and vinyl acetate, ethylene, propylene, butadiene, styrene or the like wherein the content of vinyl chloride is usually at least 60 mole % and preferably at least 80 mole %. The degree of polymerization of the vinyl chloride resin is not critical but is preferably 500 to 2,000.

As the amount of the vinylidene fluoride polymer or the vinyl chloride resin in the rubber composition increases, the resinous property of the rubber composition increases. Hence, the upper limit of the amount of said polymer or resin is governed by this property, and is preferably 60 parts by weight or less.

The proportions of the multi-component copolymer rubber and the vinylidene fluoride polymer or the vinyl chloride resin in the rubber composition of this invention can be determined appropriately within the above-mentioned ranges depending upon the application purpose and the performance requirements.

The mixing method in the preparation of the composition of this invention is not critical, but the following methods may be used:

(1) A method wherein a multi-component copolymer rubber and a vinylidene fluoride polymer or a vinyl chloride resin are blended by a mixer such as a roll, a Banbury mixer, an intermixer or the like.

(2) A method wherein a multi-component copolymer rubber and a vinylidene fluoride polymer or a vinyl chloride resin are blended in a latex or suspension state and then subjected to coagulation and subsequent coprecipitation.

(3) A method wherein the methods (1) and (2) are combined.

Into the multi-component copolymer rubber composition can optionally be incorporated conventional compounding chemicals such as a reinforcing agent, a filler, a plasticizer, a softener, a crosslinking agent, a stabilizer and the like. The resulting mixture can be subjected to crosslinking by a conventional method to easily obtain a crosslinked material.

The multi-component copolymer rubber composition of this invention is excellent not only in gasoline resistance, sour gasoline resistance, ozone resistance and heat resistance but also in new performance requirements namely, gasohol resistance and sour gasohol resistance. In addition, the composition is good in tensile strength, elongation and low-temperature resistance. Therefore, the composition can be used in fuel system hoses of automobiles; other hoses, diaphragms and seals (e.g. gaskets, O-rings, oil seals) which come in contact with fuels, hydraulic oils, lubricating oils, etc.; rolls, transfer belts and conveyor belts requiring oil resistance and solvent resistance for use in iron manufacturing, spinning, printing, paper making, dyeing, etc.; and so forth. Utilizing the characteristic feature of the multi-component copolymer rubber composition being excellent in sour gasoline resistance and sour gasohol resistance, the composition can preferably be used in fuel system hoses of automobiles.

The acrylic rubber mentioned above is a multi-component copolymer rubber consisting of (A') 99.5 to 39.5% by weight of an alkyl acrylate, (B') 0 to 60% by weight of an alkoxyalkyl acrylate, (C') 0.5 to 10% by weight of at least one compound selected from the group consisting of diene compounds, (meth)acrylic acid esters containing a dihydrodicyclopentadienyl group, epoxy group-containing, ethylenically unsaturated compounds and active halogen-containing, ethylenically unsaturated compounds and (D') 0 to 10% by weight of other ethylenically unsaturated compound copolymerizable with (A'), (B') and (C'). The nitrile rubber mentioned above is a multi-component copolymer rubber composed of (A") 20 to 90% by weight of a conjugated diolefin, (B") 10 to 55% by weight of an α,β-unsaturated nitrile, (C") 0 to 70% by weight of an α,β-unsaturated carboxylic acid ester and (D") 0 to 20% by weight of at least one monomer selected from the group consisting of carboxyl group-containing monomers, epoxy group-containing monomers, hydroxyl group-containing monomers and amino group-containing monomers.

The alkyl acrylate which is the component (A') of the acrylic rubber is represented by the formula (II): ##STR3## wherein R³ is an alkyl group having 1 to 18 carbon atoms. Specific examples of the alkyl acrylate are as mentioned hereinbefore as to the component (B).

Specific examples of the alkoxyalkyl acrylate which is the component (B') of the acrylic rubber include methoxyethyl acrylate, ethoxyethyl acrylate and butoxyethyl acrylate.

As the component (C') of the acrylic rubber, there can be used the diene compounds, the (meth)acrylic acid esters containing a dihydroxypentadienyl group, the epoxy group-containing, ethylenically unsaturated compounds and the active halogen-containing, ethylenically unsaturated compounds, all of which have been mentioned with respect to the component (C) of the multi-component copolymer rubber of this invention.

The component (D'), namely, other ethylenically unsaturated compound copolymerizable with the components (A'), (B') and (C') may be various compounds. Specific examples of the component (D') include carboxyl group-containing compounds such as acrylic acid, methacrylic acid, crotonic acid, 2-pentanoic acid, maleic acid, fumaric acid, itaconic acid and the like; methacrylates such as methyl methacrylate, octyl methacrylate and the like; alkyl vinyl ketones such as methyl vinyl ketone and the like; alkenyl alkyl ethers such as vinyl ethyl ether, allyl methyl ether and the like; alkenyl aromatic compounds such as styrene, α-methylstyrene, chlorostyrene, vinyltoluene and the like; vinylnitriles such as acrylonitrile, methacrylonitrile and the like; vinylamides such as acrylamide, methacrylamide, N-methylolacrylamide and the like; vinyl chloride; vinylidene chloride; and alkyl fumarates.

The acrylic rubber used in this invention consists of 99.5 to 39.5% by weight of the component (A'), 0 to 60% by weight of the component (B'), 0.5 to 10% by weight of the component (C') and 0 to 10% by weight of the component (D'). When the component (A') is less than 39.5% by weight, the acrylic rubber has low heat-resistance. When the component (B') exceeds 60% by weight, the rubber has low heat-resistance. When the component (C') is less than 0.5% by weight, the rubber is insufficient in crosslinkability and poor in physical properties, particularly in normal physical properties such as permanent compression set. When the component (C') exceeds 10% by weight, the rubber has low heat-resistance. When the component (D') optionally used exceeds 10% by weight, the rubber has a poor balance between oil resistance and low-temperature resistance.

The mixing ratio of the acrylic rubber and the multi-component copolymer rubber of this invention is not critical. However, in order to improve the kneadability, vulanization speed, permanent compression set and gasoline resistance of the acrylic rubber, it is desirable to use 5% by weight or more of the latter rubber. When the multi-component copolymer rubber is used in an amount of less than 5% by weight, the effect is small. In order to improve the heat resistance of the multi-component copolymer rubber, it is preferable to use 10% by weight or more of the acrylic rubber. When the acrylic rubber is used in an amount of less than 10% by weight, the effect is small.

According to this invention, the processability, vulcanization speed and permanent compression set which are the drawbacks of the conventional acrylic rubber can be improved. At the same time, it is made possible to freely control the balance of gasoline resistance, heat resistance and low-temperature resistance, and design a polymer meeting any desired object. Therefore, this invention is highly beneficial to related industries and the multi-component copolymer rubber composition of this invention can widely be used in rolls, hoses, packings, seal materials, diaphragms, etc.

The conjugated diolefin which is the component (A") of the nitrile rubber mentioned above includes butadiene, isoprene, etc.

The α,β-unsaturated nitrile of the component (B") includes acrylonitrile, methacrylonitrile, etc.

The α,β-unsaturated carboxylic acid ester of the component (C") includes methyl, ethyl, n-butyl and 2-ethylhexyl esters of acrylic and methacrylic acids.

With respect to the component (D"), the carboxyl group-containing monomer includes specifically acrylic acid, methacrylic acid, maleic acid, fumaric acid, etc. The epoxy group-containing monomer includes glycidyl (meth)acrylate, glycidyl ether, vinyl glycidyl ehter, etc. The hydroxyl group-containing monomer includes 1-hydroxypropyl (methy)acrylate, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, etc. The amino group-containing monomer includes dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dibutylaminoethyl (meth)acrylate, etc.

The content of the conjugated diolefin (A") in the nitrile rubber is 20 to 90% by weight. When the content is less than 20% by weight, the rubber is insufficient in low-temperature resistance and mechanical properties. When the content exceeds 90% by weight, the rubber is poor in heat resistance and sour gasoline resistance. The conjugated diolefin (A") in the nitrile rubber may be partially hydrogenated.

The content of the α,β-unsaturated nitrile (B") in the nitrile rubber is 10 to 55% by weight. When the content is less than 10% by weight, the rubber is poor in oil resistance. When the content exceeds 55% by weight, the rubber is poor in low-temperature resistance.

The content of the α,β-unsaturated carboxylic acid ester (C") in the nitrile rubber is 0 to 70% by weight. When the content exceeds 70% by weight, the rubber has a low tensile strength.

The content of the monomer (D") in the nitrile rubber is 0 to 20% by weight. When the content exceeds 20% by weight, the rubber has inferior low-temperature resistance or low permanent compression set.

The mixing ratio of the multi-component copolymer rubber of this invention to the nitrile rubber is 20-99 to 80-1 (weight ratio), preferably 50-95 to 50-5. When the proportion of the mixed multi-component copolymer rubber of this invention is less than 20% by weight, the rubber composition is insufficient in heat resistance, sour gasoline resistance and ozone resistance. When the ratio exceeds 99% by weight, the crosslinking reaction of the rubber composition is slow, and the freedom of selection of vulcanizing agent is reduced.

The form of the nitrile rubber used can be either a solid or a liquid as long as its molecular weight is 0.01 dl/g or more in terms of intrinsic viscosity. The form may be a mixture of a solid and a liquid depending upon the application of the rubber composition. When the intrinsic viscosity is lower than 0.01 dl/g, the rubber composition is high in extractability with oil and is not desirable as a gasoline-resistant material. The Mooney vescosity (ML₁₊₄, 100° C.) of the nitrile rubber is preferably 20 to 80.

The rubber composition of this invention can be kneaded by a conventional mixing equipment such as a roll, a Banbury mixer, an extruder and other intermixers capable of mixing the components without excessively heating.

To the rubber composition of this invention comprising the multi-component copolymer rubber and the nitrile rubber can be added conventional compounding chemicals such as a filler (e.g. carbon black, calcium carbonate, a hydrocarbon resin, a phenolic resin), a vulcanizing agent, a vulcanizing adjuvant, an anti-aging agent, a softener and the like. The vulcanization of the rusulting mixture is usually conducted at 100° to 210° C. for about 0.5 to 120 min with heating by steam, a high temperature liquid or a microwave.

By superimposing a layer consisting of the multi-component copolymer rubber of this invention and a layer consisting of other rubber, a laminate excellent in sour gasoline resistance and sour gasohol resistance can be produced.

The other rubbers include butadiene-acrylonitrile rubber, styrene-butadiene rubber, fluoro-rubber, polychloroprene, acrylic rubber, ethylenepropylene terpolymer (EPT), chlorinated polyethylene, chlorosulfonated polyethylene, silicone rubber, butyl rubber and epichlorohydrin rubber.

The layer consisting of the multi-component copolymer rubber of this invention and/or the layer consisting of the other rubbers may have incorporated thereinto an oxide or hydroxide of a metal of Groups II to IV of the Periodic Table for enhancing bonding strength. The oxide and the hydroxide include metal oxides such as magnesium oxide, aluminum oxide, zinc oxide, zinc dioxide, calcium oxide, lead (divalent and tetravalent) oxides and silicon dioxide and corresponding metal hydroxides. Of these, particularly preferred are magnesium oxide, calcium hydroxide, aluminum hydroxide and lead (divalent) oxide. The amount of the metal oxide or hydroxide added is usually 5 to 30 phr.

To the layer consisting of the multi-component copolymer rubber of this invention and the layer consisting of the other rubbers can be added conventional additives such as a reinforcing agent, a plasticizer, a processing adjuvant, a vulcanizing accelerator, a vulcanizing agent, an anti-aging agent and the like.

According to this invention, the layer consisting of the multi-component copolymer rubber of this invention and/or the layer consisting of the other rubbers may have incorporated thereinto an epoxy resin, a curing agent and a basic substance, and the two layers can be strongly vulcanization-bonded together. The vulcanizing agent may be a combination of maleic anhydride, phthalic anhydride, p-aminodiphenylamine, 2-methylimidazole and the like. The basic substance may be triethylamine, tetrabutylammonium chloride, or the lide. The above-mentioned laminate can also be produced by bonding the above vulcanized layers to one another.

Since the laminate has a thin layer of the multi-component copolymer rubber of this invention excellent in sour gasoline resistance and sour gasohol resistance, the laminate is excellent not only in sour gasoline resistance and sour gasohol resistance but also in various rubber properties. Therefore, the laminate can largely contribute to related industries and be used in rolls, hoses, diaphragms, etc.

Next, this invention will be explained more specifically referring to Examples and the accompanying drawings; however, it should not be interpreted to be restricted to the examples. In the drawings, FIGS. 1 to 3 show infrared absorption spectra of polymers of Examples 1, 10 and 17, respectively. In the Examples and the Comparative Examples, parts are by weight.

EXAMPLES 1 TO 8 AND COMPARATIVE EXAMPLES 1 TO 6

Using the monomers shown in Table 1 and the following polymerization chemicals, polymerization reaction was conducted at 10° C. in an autoclave having an internal volume of 6 liters:

    ______________________________________                                         Monomers (Details are shown                                                                         100       parts                                           in Table 1)                                                                    Water                200                                                       Alkylsulfate type soap                                                                              5                                                         Potassium phosphate  0.2                                                       FeSO.sub.4.7H.sub.2 O                                                                               0.006                                                     Trisodium salt of    0.020                                                     ethylenediaminetetracetic acid                                                 Sodium formaldehydesulfoxylate                                                                      0.08                                                      p-Menthane hydroperoxide                                                                            0.06                                                      ______________________________________                                    

When a conversion as shown in Table 1 was reached, 0.2 part, per 100 parts of monomers, of hydroquinone was added to the polymerization system to terminate the polymerization.

Then, the polymerization mixture was heated, and unreacted monomers were removed under reduced pressure. To the residue was added an aqueous calcium chloride solution to coagulate polymer crumbs. The crumbs were water-washed and dried at 50° C. under reduced pressure, to prepare copolymer samples of Examples 1 to 8 and Comparative Examples 1 to 6.

Each copolymer sample was subjected to measurement of Mooney viscosity, copolymer composition and glass transition temperature. The results are shown in Table 1.

The infrared absorption specturm of the polymer of Example 1 is shown in FIG. 1. Since this spectrum has a characteristic absorption of C.tbd.N bond at 2,250 cm⁻¹ and a characteristic absorption of C═O bond of ester at 1,730 cm⁻¹ the presence of these two bonds in the polymer was confirmed. As shown in Table 1, this polymer has a single glass transition temperature (Tg) as measured by differential thermal analysis, which implies that the polymer is a copolymer.

[Test of Characteristics of Vulcanizate]

The copolymer samples shown in Table 1 were subjected to compounding in accordance with the following formulations:

    ______________________________________                                         [Examples 1, 3, 7 and 8 and Comparative Examples 2, 3                          and 4]                                                                         (Crosslinking with organic peroxide)                                           Copolymer        100         parts                                             Stearic acid     1                                                             HAF.sup.(1) carbon black                                                                        50                                                            Peroximon F40.sup.(2)                                                                           2                                                              Note:                                                                          .sup.(1) High abrasion furnace black                                           .sup.(2) 1,3bis(t-butylperoxyisopropyl) benzene                               [Examples 2, 4, 5 and 6 and Comparative Examples 1 and 5]                      (Vulcanization with sulfur)                                                    Copolymer        100         parts                                             Zinc oxide       5                                                             Stearic acid     1                                                             HAF carbon black 50                                                            Accelerator TT.sup.(3)                                                                          0.75                                                          Sulfur           0.2                                                            Note:                                                                          .sup.(3) Tetramethylthiuram disulfide                                         [Comparative Example 6]                                                        (Butadiene-acrylonitrile rubber)                                               Copolymer        100         parts                                             Zinc oxide       5                                                             Stearic acid     1                                                             SRF.sup.(4) carbon black                                                                        60                                                            DOP.sup.(5)      5           parts                                             Accelerator TT.sup.(6)                                                                          1.5                                                           Accelerator CZ.sup.(7)                                                                          2                                                             Sulfur           0.5                                                           ______________________________________                                          Note:                                                                          .sup.(4) Semireinforcing furnace black                                         .sup.(5) Dioctyl phthalate                                                     .sup.(6) Tetramethylthiuram disulfide                                          .sup.(7) N--cyclohexyl2-benzothiazolsulfenamide                          

The compounds obtained were subjected to presscuring (at 180° C. for 20 min for Examples 1, 3, 7 and 8 and Comparative Examples 2, 3 and 4; at 170° C. for 20 min for Examples 2, 4, 5 and 6 and Comparative Examples 1 and 5; and at 160° C. for 20 min for Comparative Example 6) to obtain crosslinked rubbers.

Each crosslinked rubber was subjected to measurement of characteristics in accordance with JIS K 6301. The rubber was also subjected to measurement of sour gasoline resistance in accordance with the following test method.

[Test Method for Sour Gasoline Resistance]

A vulcanized rubber was immersed at 70° C. for 24 hr in a solution obtained by dissolving 1 g of lauryl peroxide in 99 g of Fuel C (a mixed solvent of isooctane:toluene=1:1 by volume). This 1 cycle procedure was repeated 20 times (20 cycles). Then, the rubber was dried at 100° C. for 15 hr under reduced pressure and subjected to measurment of tensile strength and elongation at break in accordance with JIS K 6301. The changes of these properties after immersion compared with those before immersion were calculated and used as criteria of the sour gasoline resistance of the rubber. The results are shown in Table 1.

As is obvious from Table 1, each of the multi-component copolymer rubbers of this invention provides a crosslinked material which is excellent in gasoline resistance, sour gasoline resistance, heat resistance and ozone resistance, good in low-temperature resistance, tensile strength and elongation and small in permanent compression set.

                                      TABLE 1                                      __________________________________________________________________________                   Example                 Comparative Example                                    1  2  3  4  5  6  7  8  1  2  3  4  5  6                         __________________________________________________________________________     Monomers fed, parts                                  Buta-                     Component (A)                                        diene                     2-Cyanoethyl acrylate                                                                        55 45 35 25 25 45       73 12       10 acrylo-                   4-Cyanobutyl acrylate           50 40       75 13    nitrile                   Component (B)                                        rubber                    Ethyl acrylate      30 60 53    47 57    85 22 84    (Acry-                    Butyl acrylate                                                                               42 52 32 12 12 52 24    24          62 loni-                     Component (C)                                        trile                     Ethylidenenorbornene                                                                         3  3  3  3  3     3  3  3  3  3  3     con-                      Dihydrodicyclopentadienyl                            tent:                     acrylate                     1                       41% by                    Component (D)                                        weight)                   Methoxyethyl acrylate     7                       25                           Conversion, % 84 87 80 89 90 92 78 81 83 88 82 90 85                           Mooney viscosity:                                                              ML.sub.1+4 100° C.                                                                    56 50 52 46 42 48 41 43 60 49 40 34 33                           Copolymer composition, %*.sup.1                                                2-Cyanoethyl acrylate                                                                        56 47 35 26 26 45       73 14       10                           4-Cyanobutyl acrylate           51 39       73 16                              Ethyl acrylate      31 59 53    46 58    83 24 81                              Butyl acrylate                                                                               41 50 31 12 12 51       24          62                           Ethylidenenorbornene                                                                         3  3  3  3  3     3  3  3  3  3  3  3                            Dihydrodicyclopentadienyl 0  2                                                 acrylate                                                                       Methoxyethyl acrylate     6  0                    25                           Glass transition temperature                                                                 -20                                                                               -27                                                                               -24                                                                               -20                                                                               -22                                                                               -28                                                                               -28                                                                               -27                                                                               -7 -16                                                                               -33                                                                               -22                                                                               -41                                                                               -22                       Tg, °C.                                                                 Kind of crosslinking agent*.sup.2                                                            PO S  PO S  S  S  PO PO S  PO PO PO S  S                         Properties of crosslinked                                                      rubber                                                                         Tensile strength, kg/cm.sup.2                                                                145                                                                               129                                                                               139                                                                               124                                                                               122                                                                               120                                                                               134                                                                               121                                                                               97 123                                                                               88 94 81 196                       Elongation, % 350                                                                               490                                                                               400                                                                               510                                                                               490                                                                               320                                                                               470                                                                               530                                                                               190                                                                               490                                                                               160                                                                               570                                                                               580                                                                               520                       Hardness, JIS-A                                                                              74 72 70 68 68 73 66 64 81 67 69 63 55  73                       Gasoline resistance (After 40° C. × 48 hr immersion in Fuel       C)                                                                             ΔV, %   +26                                                                               +34                                                                               +37                                                                               +44                                                                               +39                                                                               +36                                                                               +38                                                                               +43                                                                               +5 +61                                                                               +30                                                                               +102                                                                              +119                                                                              +41                       Sour gasoline resistance (After immersion of 70° C. × 24 hr       × 20 cycles in                                                           Fuel C containing 1% of lauryl peroxide)                                       Change of tensile                                                                            -11                                                                               -13                                                                               -22                                                                               -31                                                                               -39                                                                               -12                                                                               -25                                                                               -26                                                                               -10                                                                               -79                                                                               -16                                                                               -95                                                                               -76                                                                               -87                       strength, %                                                                    Change of elongation, %                                                                      -17                                                                               -31                                                                               -35                                                                               -12                                                                               -33                                                                               -24                                                                               -39                                                                               -46                                                                               -15                                                                               +32                                                                               -21                                                                               -72                                                                               -88                                                                               -96                       Heat resistance (150°  C. × 72 hr aging with air heating)         Change of tensile                                                                            +4 -7 +2 -3 -8 -10                                                                               -15                                                                               -11                                                                               -12                                                                               +6 -9 +13                                                                               -45                                                                               -81                       strength, %                                                                    Change of elongation, %                                                                      -23                                                                               -52                                                                               -24                                                                               -37                                                                               -41                                                                               -58                                                                               -29                                                                               -23                                                                               -56                                                                               -20                                                                               -32                                                                               -26                                                                               -67                                                                               -100                                                                     (No elongation)                 Change of hardness,                                                                          +9 +12                                                                               +11                                                                               +10                                                                               +11                                                                               +12                                                                                +14                                                                              +12                                                                               +15                                                                               +8 +13                                                                               +11                                                                               +13                                                                               +23                       JIS-A                                                                          Ozone resistance, (500 pphm,                                                                 ← No cracking for 168 hr → Cracks                    40° C., 30% elongation)                       appear-                                                                        ed in                                                                          2 hr                      Low-temperature resistance:                                                    Gehman torsion test T100, °C.                                                         -19                                                                               -25                                                                               -22                                                                               -18                                                                               -20                                                                               -27                                                                               -25                                                                               -25                                                                               -4 -14                                                                               -29                                                                               -20                                                                               -38                                                                               -20                       Permanent compression set,                                                                   19 50 24 54 57 42 22 23 47 28 20 26 70  65                       150° C. × 70 hr, %                                                __________________________________________________________________________      *.sup.1 Analysis of copolymer components                                       Component (A)                                                                  Calculated from the nitrogen content measured by Kjeldahl method.              Components (B) and (D)                                                         Calculated from the unreacted monomer amount in polymerization system          measured by gas chromatography, using the following formula:                   ##STR4##                                                                       yi: % of component i in copolymer                                              ai: Amount of component i fed                                                  bi: Amount of component i unreacted                                            A: Amount of total monomers fed                                                x: Conversion                                                                  Component (C)                                                                  Measured by iodometry.                                                         *.sup.2 PO: Crosslinking by an organic peroxide                                S: Vulcanization by sulfur                                               

EXAMPLES 9 TO 14 AND COMPARATIVE EXAMPLES 7 TO 11

The copolymer samples of Examples 9 to 14 and Comparative Examples 7 to 11 were prepared by repeating the procedure of Examples 1 to 8, except that the monomers shown in Table 2 were used.

Each copolymer sample was subjected to measurement of Mooney viscosity, copolymer composition and glass transition temperature. The results are shown in Table 2.

The infrared absorption spectrum of the polymer of Example 10 is shown in FIG. 2. Since this spectrum has a characteristic absorption of C.tbd.N bond at 2,250 cm⁻¹ and a characteristic absorption of C═O bond of ester at 1,730 cm⁻¹, the presence of these two bonds in the polymer was confirmed. As shown in Table 2, this polymer has a single glass transition temperature (Tg) as measured by differential thermal analysis, which implies that the polymer is a copolymer.

[Test of Characteristics of Vulcanizate]

The copolymer samples shown in Table 2 were subjected to compounding in accordance with the following formulations.

    ______________________________________                                         (Examples 9 to 14 and Comparative Examples 7 to 9)                             Copolymer        100         parts                                             Stearic acid     1                                                             HAF.sup.(1) carbon black                                                                        50                                                            Ammonium benzoate                                                                               1                                                              Note:                                                                          .sup.(1) High abrasion furnace black                                          (Comparative Example 10)                                                       Copolymer        100         parts                                             Stearic acid     1                                                             HAF carbon black 50                                                            Accelerator TRA.sup.(2)                                                                         0.5                                                           Accelerator EUR.sup.(3)                                                                         1                                                             Calcium stearate 3                                                              Note:                                                                          .sup.(2) Dipentamethylenethiuram hexasulfide                                   .sup.(3) 1,3-Diethylthiourea                                                  (Comparative Example 11)                                                       (Butadiene-acrylonitrile rubber)                                               Copolymer        100         parts                                             Zinc oxide       5                                                             Stearic acid     1                                                             SRF.sup.(4) carbon black                                                                        60                                                            DOP.sup.(5)      5                                                             Accelerator TT.sup.(6)                                                                          1.5                                                           Accelerator CZ.sup.(7)                                                                          2                                                             Sulfur           0.5                                                           ______________________________________                                          Note:                                                                          .sup.(4) Semi-reinforcing furnace black                                        .sup.(5) Dioctyl phthalate                                                     .sup.(6) Tetramethylthiuram disulfide                                          .sup.(7) N--cyclohexyl-2-benzothiazolsulfenamide                         

The compounds obtained were subjected to press-curing (at 175° C. for 20 min for Examples 9 to 14 and Comparative Examples 7 to 10 and at 160° C. for 20 min for Comparative Example 11) to obtain crosslinked rubbers.

Each crosslinked rubber was subjected to measurement of characteristics in accordance with JIS K 6301. The rubber was also subjected to measurement of sour gasoline resistance in accordance with the same method as in Examples 1 to 8. The results are shown in Table 2.

As is obvious from Table 2, each of the multi-component copolymer rubbers of this invention provides a crosslinked material which is excellent in gasoline resistance, sour gasoline resistance, heat resistance and ozone resistance, good in low-temperature resistance, tensile strength and elongation and small in permanent compression set.

                                      TABLE 2                                      __________________________________________________________________________                      Example           Comparative Example                                          9  10 11 12 13 14 7  8   9  10 11                             __________________________________________________________________________     Monomers fed, parts                             Butadiene-                     Component (A)                                   acrylo-                        2-Cyanoethyl acrylate                                                                           45 35 35 25       75 10     20 nitrile                        4-Cyanobutyl acrylate        60 40        75    rubber                         Component (B)                                   (Acrylo-                       Ethyl acrylate      30 30 47 37 57        22 52 nitrile                        n-Butyl acrylate 52 32 27 25       22 62     25 content:                       Component (C)                                   41% by                         Allyl glycidyl ether                                                                            3  3     3  3  3  3  3   3     weight)                        Glycidyl methacrylate  3                                                       Component (D)                                                                  Vinyl chloroacetate                                                            2-Methoxyethyl acrylate                                                                               5              25                                       Conversion, %    77 83 86 91 81 85 79 88  74 85                                Mooney viscosity, ML.sub.1+4, 100° C.                                                    41 44 45 50 36 39 57 37  35 42                                Copolymer composition, %*.sup.1                                                2-Cyanoethyl acrylate                                                                           46 36 35 25       76 10     21                                4-Cyanobutyl acrylate        61 41        76                                   Ethyl acrylate      30 30 48 36 56 21     21 52                                n-Butyl acrylate 51 31 25 24          64     25                                Allyl glycidyl ether                                                                            3  3     3  3  3  3      3                                    Glycidyl methacrylate  4                                                       Vinyl chloroacetate                       2                                    2-Methoxyethyl acrylate                                                                               6              23                                       Glass transition temperature:                                                                   -30                                                                               -26                                                                               -25                                                                               -26                                                                               -35                                                                               -31                                                                               -9 -46 -35                                                                               -26                                                                               -22                            Tg, °C.                                                                 Properties of crosslinked                                                      rubber                                                                         Tensile strength, kg/cm.sup.2                                                                   142                                                                               157                                                                               138                                                                               164                                                                               133                                                                               120                                                                               102                                                                               95  116                                                                               144                                                                                196                           Elongation, %    450                                                                               360                                                                               300                                                                               420                                                                               490                                                                               530                                                                               110                                                                               570 170                                                                               480                                                                                520                           Hardness, JIS-A  68 68 70 66 66 63 81 51  69 62  73                            Gasoline resistance (After immersion in Fuel C at 40° C. for 48         hr)                                                                            ΔV, %      +33                                                                               +39                                                                               +36                                                                               +47                                                                               +35                                                                               +45                                                                               +4 +121                                                                               +27                                                                               +58                                                                               +41                            Sour gasoline resistance (After immersion of 70° C. × 24 hr       × 20 cycles in                                                           Fuel C containing 1% of lauroyl peroxide) -                                    Change of tensile                                                                               -18                                                                               -28                                                                               -26                                                                               -41                                                                               -17                                                                               -19                                                                               -6 -72 -13                                                                               -91                                                                               -87                            strength, %                                                                    Change of elongation, %                                                                         -38                                                                               -38                                                                               -47                                                                               -11                                                                               -22                                                                               -37                                                                               -17                                                                               -86 -15                                                                               -72                                                                               -96                            Heat resistance (150° C. × 72 hr aging with air heating)          Change of tensile                                                                               +3 +6 -11                                                                               -2 -14                                                                               -8 -10                                                                               -39 -20                                                                               +2 -81                            strength, %                                                                    Change of elongation, %                                                                         -44                                                                               -34                                                                               -46                                                                               -23                                                                               -49                                                                               -43                                                                               -51                                                                               - 60                                                                               -55                                                                               -22                                                                               -100                                                                        (No elongation)                   Change of hardness, JIS-A                                                                       +13                                                                               +12                                                                               +13                                                                               +9 +15                                                                               +13                                                                               +14                                                                               +15 +18                                                                               +7 +23                            Ozone resistance, (500 pphm,                                                                    ← No cracking for 168 hr →                                                                        Cracks                         40° C., 30% elongation)                  appeared                                                                       in 2 hr                        Low-temperature resistance:                                                    Gehman torsion test T100, °C.                                                            -28                                                                               -24                                                                               -24                                                                               -25                                                                               -33                                                                               -28                                                                               -6 -41 -30                                                                               -23                                                                               -20                            Permanent compression set,                                                                      44 48 51 52 50 54 27 67  46 64  65                            150°  C. × 70 hr, %                                               __________________________________________________________________________      *.sup.1 Analysis of copolymer components                                       Cyanoalkyl acrylates:                                                          Calculated from the nitrogen content measured by Kjeldahl method.              Alkyl acrylates and other monomers:                                            Calculated from the unreacted monomer amount in polymerization system          measured by gas chromatography, using the following formula.                   ##STR5##                                                                       yi: % of component i in copolymer                                              ai: Amount of component i fed                                                  bi: Amount of component i unreacted                                            x: Conversion                                                            

EXAMPLES 15 TO 19 AND COMPARATIVE EXAMPLES 12 TO 17

The copolymer samples of Examples 15 to 19 and Comparative Examples 12 to 17 were prepared by repeating the procedure of Examples 1 to 8, except that the monomers shown in Table 3 were used.

Each copolymer sample was subjected to measurement of Mooney viscosity, copolymer composition and glass transition temperature. The results are shown in Table 3.

The infrared absorption spectrum of the copolymer of Example 17 is shown in FIG. 3. Since this spectrum has a characteristic absorption of C.tbd.N bond at 2,250 cm⁻¹ and a characteristic absorption of C═O bond of ester at 1,730 cm³¹ 1, the presence of these two bonds in the copolymer was confirmed. As shown in Table 3, this copolymer has a single glass transition temperature (Tg) as measured by differential thermal analysis, which implies that the product is a copolymer.

[Test of Characteristics of Vulcanizate]

The copolymer samples shown in Table 2 were subjected to compounding in accordance with the following formulations.

[Examples 15 to 19 and Comparative Examples 12 to 16]

The same formulation as in Comparative Example 10.

[Comparative Example 17]

The same formulation as in Comparative Example 11.

The compounds obtained were subjected to press-curing (at 175° C. for 20 min for Examples 15 to 19 and Comparative Examples 12 to 16 and at 160° C. for 20 min for Comparative Example 17) to obtain crosslinked rubbers.

Each crosslinked rubber was subjected to measurement of characteristics in accordance with JIS K 6301. The rubber was also subjected to measurement of sour gasoline resistance in accordance with the same method as in Examples 1 to 8.

As is obvious from Table 3, each of the multi-component copolymer rubbers of this invention provides a crosslinked material which is excellent in gasoline resistance, sour galosine resistance, heat resistance and ozone resistance, good in low temperature resistance, tensile strength and elongation and small in permanent compression set.

                                      TABLE 3                                      __________________________________________________________________________                      Example        Comparative Example                                             15 16 17 18 19 12 13  14 15 16    17                          __________________________________________________________________________     Monomers fed, parts                                Butadiene-                  Cyano-substituted alkyl                            acrylo-                     acrylates                                          nitrile                     2-Cyanoethyl acrylate                                                                           55 35 45       73 10        0.5   rubber                      4-Cyanobutyl acrylate     50 40        75 20       (Acrylo-                    Alkyl acrylates                                    nitrile                     Ethyl acrylate      30    47 57        22 77 20.5  content:                    Butyl acrylate   42 32 52       24 62        78    41% by                      Other comonomers                                   weight)                     Vinylbenzyl chloride                                                                            3  3           3  3                                           Vinyl chloroacetate    3  3  3         3  3  1                                 Methoxyethyl acrylate              25                                          Conversion, %    86 81 81 88 85 78 88  82 84 83                                Mooney viscosity, ML.sub.1+4, 100° C.                                                    47 42 49 37 40 54 36  33 31 2.9                               Copolymer composition, %*.sup.1                                                2-Cyanoethyl acrylate                                                                           55 35 47       74 11        0.5                               4-Cyanobutyl acrylate     53 42        74 20                                   Ethyl acrylate      31    45 56        24 78 21.5                              Butyl acrylate   42 32 51       23 61        77                                Vinylbenzyl chloride                                                                            3  2           3  3                                           Vinyl chloroacetate    2  2  2     25  2  2                                    Methoxyethyl acrylate                        1                                 Glass transition temperature:                                                                   -20                                                                               -24                                                                               -28                                                                               -31                                                                               -29                                                                               -10                                                                               -43 -35                                                                               -25                                                                               -46   -22                         Tg, °C.                                                                 Properties of crosslinked                                                      rubber                                                                         Tensile strength, kg/cm.sup.2                                                                   159                                                                               145                                                                               164                                                                               151                                                                               138                                                                               109                                                                               86  121                                                                               117                                                                               56     196                        Elongation, %    290                                                                               410                                                                               460                                                                               480                                                                               550                                                                               130                                                                               540 180                                                                               620                                                                               610    520                        Hardness, JIS-A  70 64 66 65 63 77 52  68 61 50     73                         Gasoline resistance (After immersion in Fuel C at 40° C. for 48         hr)                                                                            ΔV, %      +28                                                                               +42                                                                               +35                                                                               +38                                                                               +44                                                                               +4 +117                                                                               +29                                                                               +85                                                                               +190  +41                         Sour gasoline resistance (After immersion of 70° C. × 24 hr       × 20 cycles in                                                           Fuel C containing 1% of lauroyl peroxide)                                      Change of tensile                                                                               -21                                                                               -32                                                                               -23                                                                               -29                                                                               -29                                                                               -8 -83 -14                                                                               -94                                                                               Impos-                                                                               -87                         strength, %                                  sible                             Change of elongation, %                                                                         -32                                                                               -45                                                                               -26                                                                               -39                                                                               -44                                                                               -20                                                                               -85 -21                                                                               -67                                                                               to measure                                                                           -96                                                                      due to                                                                         high soft-                                                                     ness                              Heat resistance (150° C. × 72 hr aging with air heating)          Change of tensile                                                                               -6 +1 -4 -16                                                                               -10                                                                               +23                                                                               -41 -21                                                                               +25                                                                               +11   -81                         strength, %                                                                    Change of elongation, %                                                                         -44                                                                               -38                                                                               -47                                                                               -47                                                                               -39                                                                               -51                                                                               -63 -54                                                                               -30                                                                               -24   -100                                                                     (No elongation)                   Change of hardness, JIS-A                                                                       +8 +13                                                                               +10                                                                               +15                                                                               +14                                                                               +18                                                                               +14 +19                                                                               +9 +8    +23                         Ozone resistance (500 pphm,                                                                     ← No cracking for 168 hr →                                                                           Cracks                      40° C., 30% elongation)                     appeared                                                                       in 2 hr                     Low-temperature resistance:                                                    Gehman torsion test T100, °C.                                                            -17                                                                               -22                                                                               -25                                                                               -29                                                                               -26                                                                               -7 -37 -31                                                                               -22                                                                               -42   -20                         Permanent compression set,                                                                      49 56 53 52 55 42 68  47 62 57     65                         150° C. × 70 hr, %                                                __________________________________________________________________________      *.sup.1 Analysis of copolymer components                                       Cyanoalkyl acrylates:                                                          Calculated from the nitrogen content measured by Kjeldahl method.              Alkyl acrylates and other monomers:                                            Calculated from the unreacted monomer amount in polymerization system          measured by gas chromatography, using the following formula:                   ##STR6##                                                                       yi: % of component i in copolymer                                              ai: Amount of component i fed                                                  bi: Amount of component i unreacted                                            x: Conversion                                                            

EXAMPLES 20 TO 25 AND COMPARATIVE EXAMPLE 18

The copolymers shown in Table 4 were subjected to compounding in accordance with the formulations shown in Table 5 and kneaded by a roll to obtain unvulcanized rubber compounds. These unvulcanized rubber compounds were subjected to press-curing (at 175° C. for 20 min for Examples 20 to 25 and at 160° C. for 20 min for Comparative Example 18) to obtain vulcanized rubbers. The vulcanized rubbers were subjected to measurement of characteristics in accordance with JIS K 6301. The rubbers were also subjected to measurement of sour gasoline resistance by the same method as in Examples 1 to 8.

As is obvious from Table 4, the vulcanized rubber compositions of this invention ar excellent in sour gasoline resistance and heat resistance and good in tensile strength and elongation.

                                      TABLE 4                                      __________________________________________________________________________                                       Comparative                                                  Example           Example                                                      20 21 22 23 24 25  18                                          __________________________________________________________________________     Copolymer composition, %*.sup.1   Butadiene- -2-Cyanoethyl                                                       acrylate 57 46 36 47   acrylonitrile         4-Cyanoethyl acrylate       53 42 rubber                                       Ethyl acrylate        30    45 56 (Acrylonit-                                  Butyl acrylate  40 51 31 51       rile content:                                Allyl glycidyl ether                                                                           3  3  3           41% by weight)                               Vinyl chloroacetate      2  2  2                                               Crosslinking agents, parts                                                     Hexamethylenetetramine                                                                         0.5                                                            Zinc dimethyldithiocarbamate                                                                      0.3                                                         Potassium stearate    2.5                                                                               0.5                                                   Sodium stearate       1  2.5                                                   Sulfur                0.2                                                                               0.3                                                   Ammonium benzoate           3                                                  Hexamethylenediamine carbamate 0.5                                             Properties of crosslinked rubber                                               Tensile strength, kg/cm.sup.2                                                                  160                                                                               138                                                                               165                                                                               171                                                                               160                                                                               141                                                                               196                                          Elongation, %   300                                                                               470                                                                               380                                                                               450                                                                               430                                                                               560                                                                               520                                          Hardness, JIS-A 70 67 68 67 64 62  73                                          Sour gasoline resistance (After immersion of 70° C. × 24 hr       × 20 cycles in Fuel C containing 1% of lauroyl peroxide)                 Change of tensile strength, %                                                                  -13                                                                               -20                                                                               -25                                                                               -17                                                                               -30                                                                               -27                                                                               -87                                          Change of elongation, %                                                                        -25                                                                               -39                                                                               -40                                                                               -22                                                                               -37                                                                               -41                                                                               -96                                          Heat resistance (150 ° C. × 72 hr aging with air heating)         Change of tensile strength, %                                                                  -5 +2 +5 +2 -7 -8 -81                                          Change of elongation, %                                                                        -43                                                                               -45                                                                               -30                                                                               -41                                                                               -46                                                                               -43                                                                               -100                                                                           (No elongation)                              Change of hardness, JIS-A                                                                      +12                                                                               +13                                                                               +10                                                                               +10                                                                               +11                                                                               +14                                                                               +23                                          __________________________________________________________________________      *.sup.1 Analysis of copolymer components                                       Cyanoalkyl acrylates: Calculated from the nitrogen content measured by         Kjeldahl method.                                                               Alkyl acrylates and other monomers: Calculated from the unreacted monomer      amount in polymerization system meausred by gas chromatography, using the      following formula:                                                             ##STR7##                                                                       yi: % of component i in copolymer                                              ai: Amount of component i fed                                                  bi: Amount of component i unreacted                                            x: Conversion                                                            

                  TABLE 5                                                          ______________________________________                                         Compound formulation                                                           ______________________________________                                         Examples 20 to 25                                                              Polymer            100        parts                                            HAF carbon black   50                                                          Stearic acid       1                                                           Crosslinking agent Shown in Table 1                                            Comparative Example 18                                                         Polymer            100        parts                                            Zinc oxide         5                                                           Stearic acid       1                                                           SRF carbon black   60                                                          DOP                5                                                           Vulcanization accelerator TT*.sup.1                                                               1.5                                                         Vulcanization accelerator CZ*.sup.2                                                               2                                                           Sulfur             0.5                                                         ______________________________________                                          *.sup.1 Tetramethylthiuram disulfide                                           *.sup.2 N--cyclohexyl-2-benzothiazolsulfenamide                          

EXAMPLES 26 TO 34 AND COMPARATIVE EXAMPLES 19 TO 23

Using the monomers shown in Table 7 and the following polymerization chemicals, polymerization reaction was conducted at 10° C. in an autoclave having an internal volume of 6 liters:

    ______________________________________                                         Monomers (Details are shown in                                                                      100       parts                                           Table 7)                                                                       Water                200                                                       Alkylsulfate type soap                                                                              5                                                         Potassium phosphate  0.2                                                       FeSO.sub.4.7H.sub.2 O                                                                               0.006                                                     Trisodium salt of    0.020                                                     ethylenediaminetetracetic acid                                                 Sodium formaldehydesulfoxylate                                                                      0.08                                                      p-Menthane hydroperoxide                                                                            0.06                                                      ______________________________________                                    

When a conversion shown in Table 7 was obtained, 0.2 part of hydroquinone per 100 parts of monomers was added to the polymerization system to terminate the polymerization.

Then, the polymerization mixture was heated, and the unreacted monomers were removed under reduced pressure. To the residue was added an aqueous calcium chloride solution to coagulate polymer crumbs. The crumbs were water-washed and dried at 50° C. under reduced pressure, whereby the copolymers of Examples 26 to 34 and Comparative Examples 19 to 23 were prepared. These copolymers were compounded with the formulations show in Table 6 and kneaded by a Banbury mixer. The kneaded compounds were subjected to evaluation of processability from dischargability from Banbury mixer as well as from knitting performance, and good processability was indicated as o, and bad processability as X.

The compounded rubbers obtained were subjected to press-curing at 175° C. for 20 min to obtain vulcanized rubbers. The vulcanized rubbers were subjected to measurement of characteristics in accordance with JIS K 6301. These rubbers were also subjected to measurement of sour gasoline resistance in accordance with the following method.

[Test Method for Sour Gasoline Resistance]

A vulcanized rubber was immersed at 70° C. for 24 hr in a solution obtained by dissolving 1 g of lauryl peroxide in 99 g of Fuel C (a mixed solvent of isooctane: toluene=1:1 by volume). This 1 cycle procedure was repeated 20 times (20 cycles). Then, the rubber was dried at 100° C. for 15 hr under reduced pressure and subjected to measurement of tensile strength and elongation in accordance with JIS K 6301. The change (%) of the value obtained after immersion relative to the value obtained before immersion was calculated and used as criteria of the sour gasoline resistance of the rubber. The results are shown in Table 7.

As is obvious from Table 7, the multi-component copolymer rubbers of this invention have good kneadability and the vulcanized rubbers obtained therefrom are excellent in sour gasoline resistance and heat resistance and good in tensile strength and elongation.

                                      TABLE 6                                      __________________________________________________________________________                A   B   C   D   E   F   G   H   I   J                               __________________________________________________________________________     Copolymer  100 100 100 100 100 100 100 100 100 100                             Stearic acid                                                                              1   1   5   1   1   1   1   1   1   1                               HAF carbon black                                                                          50  50  50  50  50  50  50  50  50  50                              Ammonium benzoate                                                                         1   1   1   1   1   1   1   1   1   1                               TE-80*.sup.1                                                                              3   1                   0.2 15      3                               Paraffin wax*.sup.2    5                                                       VANFRE AP-2*.sup.3         3                                                   GAFAC RL210*.sup.4             3                                               RS 700*.sup.5                                  5                               __________________________________________________________________________      *.sup.1 Sodium salt of a fatty acid, manufactured by Du Pont                   *.sup.2 Hydrocarbon type compound                                              *.sup.3 Fatty acid ester type compound, manufactured by IPPOSHA OIL            INDUSTRY CO., LTD.                                                             *.sup.4 Phosphoric acid ester type compound, manufactured by Toho Chemica      Industries Co., Ltd.                                                           *.sup.5 Polyetherester compound (plasticizer)                            

                                      TABLE 7                                      __________________________________________________________________________                      Example                 Comparative Example                                                                             Example                               26 27 28 29 30 31 32 33 19 20 21  22 23  34                   __________________________________________________________________________     Monomers fed, parts                                                            Component (A)                                                                  2-Cyanoethyl acrylate                                                                           45 35    45 45 45 45 45 45 45 45  35     45                   4-Cyanobutyl acrylate  60                             60                       Component (B)                                                                  Ethyl acrylate      30 37                          30 37                       n-Butyl acrylate 52 27    52 52 52 52 52 52 52 52  27     52                   Component (C)                                                                  Allyl glycidyl ether                                                                            3     3  3  3  3  3  3  3  3  3      3   3                    Glycidyl methacrylate                                                                              3                              3                           Component (D)                                                                  Vinyl chloroacetate                                                            2-Methoxyethyl acrylate                                                                            5                              5                           Conversion, %    77 86 81 77 77 77 77 77 77 77 77  86 81  77                   Mooney viscosity, ML.sub.1+4, 100° C.                                                    41 45 36 41 41 41 41 41 41 41 41  45 36  41                   Copolymer composition, %*.sup.1                                                2-Cyanoethyl acrylate                                                                           46 35    46 46 46 46 46 46 46 46  35     46                   4-Cyanobutyl acrylate  61                             61                       Ethyl acrylate      30 36                          30 36                       n-Butyl acrylate 51 25    51 51 51 51 51 51 51 51  25     51                   Allyl glycidyl ether                                                                            3     3  3  3  3  3  3  3  3  3      3    3                   Glycidyl methacrylate                                                                              4                              4                           Vinyl chloroacetate                                                            2-Methoxyethyl acrylate                                                                            6                              6                           Glass transition temperature:                                                                   -30                                                                               -25                                                                               -35                                                                               -30                                                                               -30                                                                               -30                                                                               -30                                                                               -30                                                                               -30                                                                               -30                                                                               -30 -25                                                                               -35 -30                  Tg, °C.                                                                 Compound formulation                                                                            A  A  A  B  C  D  E  F  G  H  I   I  I   J                    Processability   o  o  o  o  o  o  o  o  x  o  x   x  x   o                    Properties of crosslinked                                                      rubber                                                                         Tensile strength, kg/cm.sup.2                                                                   138                                                                               132                                                                               130                                                                               140                                                                               137                                                                               139                                                                               138                                                                               120                                                                               142                                                                               85 142 138                                                                               133 130                  Elongation, %    460                                                                               330                                                                               520                                                                               450                                                                               470                                                                               480                                                                               480                                                                               530                                                                               450                                                                               610                                                                               450 300                                                                               490 500                  Hardness, JIS-A  66 67 65 67 68 67 67 65 68 58 68  70 66  63                   Gasoline resistance (After immersion of 40° C. × 48 hr in         Fuel C)                                                                        ΔV, %      +26                                                                               +30                                                                               +28                                                                               +30                                                                               +30                                                                               +31                                                                               +30                                                                               +28                                                                               +31                                                                               +23                                                                               +33 +36                                                                               +35 +21                  Sour gasoline resistance (After immersion of 70° C.× 24 hr        × 20 cycles in Fuel C containing 1% of lauroyl peroxide)                 Change of tensile                                                                               -14                                                                               -19                                                                               -15                                                                               -17                                                                               -20                                                                               -15                                                                               -14                                                                               -20                                                                               -17                                                                               -23                                                                               -18 -26                                                                               -17 -10                  strength, %                                                                    Change of elongation, %                                                                         -35                                                                               -35                                                                               -25                                                                               -39                                                                               -40                                                                               -35                                                                               -40                                                                               -42                                                                               -40                                                                               -45                                                                               -38 -47                                                                               -22 -32                  Heat resistance (150° C. × 72 hr aging with air heating)          Change of tensile                                                                               -1 -7 -10                                                                               -2 -5 -5 -7 -1 +2 -7 +3  -1 -14 +5                   strength, %                                                                    Change of elongation, %                                                                         -48                                                                               -48                                                                               -51                                                                               -43                                                                               -46                                                                               -48                                                                               -48                                                                               -47                                                                               -45                                                                               -51                                                                               -44 -46                                                                               -49 -50                  Change of hardness, JIS-A                                                                       +15                                                                               +15                                                                               +17                                                                               +14                                                                               +14                                                                               +14                                                                               +14                                                                               +15                                                                               +13                                                                               +18                                                                               +13 +13                                                                               +15 +17                  Ozone resistance (50 pphm, 40° C., 30% elongation)                                       ← No cracking for 168 hr →                        Low-temperature resistance:                                                                     -30                                                                               -25                                                                               -35                                                                               -29                                                                               -29                                                                               -29                                                                               -29                                                                               -30                                                                               -28                                                                               -33                                                                               -28 -24                                                                               -33 -36                  Gehman torsion test                                                            T100, °C.                                                               Permanent compression set,                                                                      45 52 52 44 45 46 45 46 44 54 44  51 50  47                   150° C. × 70 hr, %                                                __________________________________________________________________________      *.sup.1 Analysis of copolymer coponents                                        Component (A)                                                                  Calculated from the nitrogen content measured by Kjeldhl method.               Components (B) and (C)                                                         Calculated from the unreacted monomer amount in polymerization system          measured by gas chromatography, using the following formula:                   ##STR8##                                                                       yi: % of component i in copolymer                                              ai: Amount of component i fed                                                  bi: Amount of component i unreacted                                            A: Amount of total monomers fed                                                x: Conversion                                                                  Component (C)                                                                  Measured by iodometry.                                                   

EXAMPLES 35 TO 42 AND COMPARATIVE EXAMPLES 24 TO 28

Each polymer composition sample consisting of a multi-component copolymer rubber and a fluororubber whose formulation is shown in the upper section of Table 9 was compounded by a Banbury mixer with the formulation shown in Table 8. Each compound obtained was press-cured under the conditions shown in the lower section of Table 8.

The crosslinked rubber compositions thus obtained were subjected to measurement of characteristics in accordance with JIS K 6301.

These rubber compositions were also subjected to sour gasoline resistance and sour gasohol resistance in accordance with the following method.

[Test Method for Sour Gasoline Resistance]

A test specimen of a crosslinked rubber composition was immersed at 40° C. for 72 hr in a solution obtained by dissolving 2.5 g of lauryl peroxide in 97.5 g of Fuel C (a mixed solvent consisting of equal volumes of isooctane and toluene). This 1 cycle procedure was repeated n times (n cycles). After each cycle, the test specimen was taken out, dried at 100° C. for 15 hr under reduced pressure and bent at an angle of 180° to observe formation of cracks.

[Test Method for Sour Gasohol Resistance]

This resistance was measured by the same method as in the case of sour gasoline resistance, except that Fuel C was replaced by a mixed solvent consisting of 80 parts by volume of Fuel C and 20 parts by volume of ethanol.

The measurement results are shown in the lower section of Table 9.

As is obvious from Table 9, the multi-component copolymer rubber compositions of this invention are excellent not only in gasoline resistance, gasohol resistance, sour gasoline resistance, sour gasohol resistance, ozone resistance and heat resistance but also in tensile strength, elongation and balance between gasoline resistance and low-temperature resistance.

                                      TABLE 8                                      __________________________________________________________________________                  Compound Symbol                                                                K     L     M     N     O                                         __________________________________________________________________________     Polymer composition                                                                         100.0 100.0 100.0 100.0 100.0                                     Zinc oxide   5.0                                                               Stearic acid 1.0   1.0   1.0   1.0   1.0                                       HAF carbon black*.sup.1                                                                     20.0  20.0  20.0  20.0  60.0                                      Processing aid TE-80*.sup.2                                                                 1.0   1.0   1.0   1.0   1.0                                       Accelerator TT*.sup.3                                                                       0.75                                                              Accelerator TRA*.sup.4         0.5                                             Accelerator EUR*.sup.5         1.0                                             Sulfur       0.2                                                               Peroximon F40*.sup.6                                                                              2.0                                                         Ammonium benzoate        2.0         2.0                                       Potassium stearate             3.0                                             Conditions for press-curing                                                                 165° C. ×                                                               180° C. ×                                                               165° C. ×                                                               175° C. ×                                                               165° C. ×                                 30 min                                                                               20 min                                                                               30 min                                                                               20 min                                                                               30 min                                    __________________________________________________________________________      *.sup.1 High abrasion furnace black                                            *.sup.2 Metal salt of a fatty acid, manufactured by Technical Processing       Co.                                                                            *.sup.3 Tetramethylthiuram disulfide                                           *.sup.4 Dipentamethylenethiuram hexasulfide                                    *.sup.5 1,3-Diethylthiourea                                                    *.sup.6 1,3-Bis(t-butylperoxyisopropyl)benzene                           

                                      TABLE 9                                      __________________________________________________________________________                     Example                 Comparative Example                                    35 36 37 38 39 40 41 42 24  25 26  27 28                       __________________________________________________________________________     Multi-component copolymer                                                                      70 70 70 70 70 70 90 50 70  70 97  70 28                       rubber, parts                                                                  Component (A) composition (%)                                                  2-Cyanoethyl acrylate                                                                          56 35 25 25    25 25 25     86 25  25 25                       4-Cyanobutyl acrylate       42                                                 Component (B) composition (%)                                                  Ethyl acrylate     31 53 47 56 47 47 47 97     47  47 47                       n-Butyl acrylate                                                                               41 31 12 25    25 25 25     11 25  25 25                       Component (C) composition (%)                                                  Ethylidenenorbornene                                                                           3  3  3                 3   3                                  Allyl glycidyl ether     3     3  3  3         3      3                        Vinyl chloroacetate         2                      3                           Component (D) composition (%)                                                  Methoxyethyl acrylate 7                                                        Fluororubber, parts                                                            JSR KYNAR 731*.sup.1                                                                           30 30 30 30 30    10 50 30  30 3                               VITON GF*.sup.2                30                                              JSR AFLAS*.sup.3                                   30                          Compound symbol*.sup.4                                                                         K  L  K  M  N  O  M  M  K   K  O   O  M                        Properties of crosslinked rubber                                               Tensile strength, kg/cm.sup.2                                                                  210                                                                               202                                                                               198                                                                               195                                                                               193                                                                               155                                                                               165                                                                               240                                                                               185 121                                                                               151 150                                                                               150                      Elongation, %   250                                                                               265                                                                               270                                                                               265                                                                               275                                                                               350                                                                               320                                                                               190                                                                               255 150                                                                               350 370                                                                               350                      Hardness, JIS-A 71 70 69 72 71 72 65 75 72  75 66  73 66                       Gasoline resistance (After immersion of 40° C. × 48 hr in         Fuel C)                                                                        ΔV, %     +8 +15                                                                               +27                                                                               +32                                                                               +41                                                                               +35                                                                               +45                                                                               +25                                                                               +105                                                                               +3 +48 +60                                                                               +49                      Gasohol resistance (After immersion of 40° C. × 48 hr in a        solution of                                                                    Fuel C/ethanol = 80/20)                                                        ΔV, %     +26                                                                               +35                                                                               +55                                                                               +67                                                                               +67                                                                                +80                                                                              +85                                                                               +49                                                                               +150                                                                               +11                                                                               +130                                                                               +97                                                                               +132                     Sour gasoline resistance (After immersion of 40° C. × 72 hr       × n cycles in                                                            Fuel C containing 2.5% of lauroyl peroxide)                                    n×3 (3 cycles)                                                                           NC*.sup.5                                                                         NC NC NC NC NC NC NC Soft-                                                                              NC NC  NC NC                                                               ened                                   n×10 (10 cycles)                                                                         NC NC NC NC NC NC NC NC Soft-                                                                              NC NC  NC NC                                                               ened                                   Sour gasohol resistance (After immersion of 40° C. × 72 hr        × n cycles in a solution                                                 consisting of 80 volume % of Fuel C containing 2.5% of lauroyl peroxide        and                                                                            20 volume % of ethanol)                                                        n×3 (3 cycles)                                                                           NC NC NC NC NC NC NC NC Soft-                                                                              NC NC  NC NC                                                               ened                                   n× 6 (6 cycles)                                                                          NC NC NC NC NC NC NC NC Soft-                                                                              NC NC  NC NC                                                               ened                                   n×10 (10 cycles)                                                                         NC NC NC NC NC NC NC NC Soft-                                                                              NC NC  NC NC                                                               ened                                   Heat resistance (150°  C. × 72 hr aging with air heating)         Change of tensile strength, %                                                                  +3 +1 +6 +5 +2 +5 +10                                                                               +1 +12 +1 +11 +5 +12                      Change of elongation, %                                                                        -40                                                                               -31                                                                               -19                                                                               -22                                                                               -23                                                                               -38                                                                               -45                                                                               -19                                                                               -16 -80                                                                               -59 -45                                                                               -59                      Change of hardness, JIS-A                                                                      +6 +5 +3 +2 +4 +10                                                                               +4 +3 +5  +18                                                                               +5  +12                                                                               +6                       Ozone resistance, static (80 pphm, 40° C., 100% elongation)             24 hr           NC NC NC NC NC NC  NC                                                                               NC NC  NC NC  NC NC                       Ozone resistance, dynamic (80 pphm, 40° C., 0 to 20% elongation)        24 hr           NC NC NC NC NC NC NC NC NC  NC NC  NC NC                       288 hr          NC NC NC NC NC NC NC NC NC  NC NC  NC NC                       Low-temperature resistance:                                                    Gehman torsion test T100, °C.                                                           -23                                                                               -25                                                                               -24                                                                               -31                                                                               -32                                                                               -21                                                                               -27                                                                               -35                                                                               -15 -5 -24 -19                                                                               -24                      __________________________________________________________________________      *.sup.1 Poly(vinylidene fluoride), manufactured by Penwalt Co.                 *.sup.2 Vinylidene fluoride type fluororubber, manufactured by Du Pont         *.sup.3 Tetrafluoroethylene-propylene type fluororubber, manufactured by       Asahi Glass Co., Ltd.                                                          *.sup.4 Refer to Table 8.                                                      *.sup.5 No cracking                                                      

EXAMPLES 43 TO 47 AND COMPARATIVE EXAMPLES 29 TO 31

Each sample of multi-component copolymer rubber/vinyl chloride resin (hereinafter referred to as PVC) compositions (Examples 43 to 47 and Comparative Examples 29 to 30) and a butadiene-acrylonitrile rubber (hereinafter referred to as NBR)/PVC composition (Comparative Example 31) was compounded by a Banbury mixer in accordance with the formulation shown in Table 10. Each compound obtained was press-cured under the conditions shown in the lower section of Table 10.

The crosslinked rubber compositions obtained were subjected to measurement of characteristics in accordance with JIS K 6301.

These compositions were also subjected to measurement of sour gasoline resistance and sour gasohol resistance in the same methods as in Examples 35 to 42, except that methanol was substituted for the ethanol.

The measurement results are shown in the lower part of Table 11.

As is obvious from Table 11, the multi-component copolymer rubber compositions of this invention are excellent not only in sour gasoline resistance, sour gasohol resistance, ozone resistance and heat resistance but also in tensile strength, elongation and balance between gasoline resistance and low-temperature resistance.

EXAMPLES 48 TO 52 AND COMPARATIVE EXAMPLE 32

There were prepared compositions each consisting of the same copolymer (2-cyanoethyl acrylate/ethyl acrylate/n-butyl acrylate/ethylidenenorbornene=35/31/31/3 by weight) and the same PVC but having a different formulation. These compositions were compounded by a Banbury mixer with the formulations shown in the upper section of Table 12.

The crosslinked rubber compositions obtained were subjected to measurement of characteristics by the same methods as in Example 43. The results are shown in the lower part of Table 12.

As is obvious from Table 12, the multi-component copolymer rubber compositions of this invention are excellent in sour gasoline resistance and sour gasohol resistance, good in tensile strength and elongation and has a practically satisfactory level of a permanent compression set.

                                      TABLE 10                                     __________________________________________________________________________                  Compound symbol                                                                P     Q     R     S     T                                         __________________________________________________________________________     Polymer      100.0 100.0 100.0 100.0 100.0                                     Zinc oxide   5.0                     5.0                                       Stearic acid 1.0   1.0   1.0   1.0   1.0                                       SRF carbon black*.sup.1                                                                     50.0  50.0  50.0  50.0  30.0                                      DOP*.sup.2   5.0   5.0   5.0   5.0   5.0                                       Accelerator TT*.sup.3                                                                       0.75                    1.5                                       Accelerator CZ*.sup.4                2.0                                       Accelerator TRA*.sup.5         0.5                                             Accelerator EUR*.sup.6         1.0                                             Sulfur       0.2                     0.5                                       Peroximon F40*.sup.7                                                                              2.0                                                         Ammonium benzoate        1.0                                                   Potassium stearate             3.0                                             Conditions for press-curing                                                                 170° C. ×                                                               180° C. ×                                                               175° C. ×                                                               175° C. ×                                                               160° C. ×                                 20 min                                                                               20 min                                                                               20 min                                                                               20 min                                                                               20 min                                    __________________________________________________________________________      *.sup.1 Semi-reinforcing furnace black                                         *.sup.2 Dioctyl phthalate                                                      *.sup.3 Tetramethylthiuram disulfide                                           *.sup.4 N--cyclohexyl-2-benzothiazolsulfenamide                                *.sup.5 Dipentamethylenethiuram hexasulfide                                    *.sup.6 1,3-Diethylthiourea                                                    *.sup.7 1,3-Bis(t-butylperoxyisopropyl)benzene                           

                                      TABLE 11                                     __________________________________________________________________________                    Example         Comparative Example                                            43  44 45 46 47 29   30 31                                      __________________________________________________________________________     Multi-component copolymer                                                                     70  70 70 70 70 70   70 70*.sup.1 (NBR)                         rubber, parts                                                                  Component (A) composition (%)                                                  2-Cyanoethyl acrylate                                                                         56  35 25 36         86                                         4-Cyanobutyl acrylate       42                                                 Component (B) composition (%)                                                  Ethyl acrylate     31 53 30 56 97                                              n-Butyl acrylate                                                                              41  31 12 31         11                                         Component (C) composition (%)                                                  Ethylidenenorbornene                                                                          3   3  3        3    3                                          Allyl glycidyl ether     3                                                     Vinyl chloroacetate         2                                                  Component (D) composition (%)                                                  Methoxyethyl acrylate 7                                                        PVC*.sup.2, parts                                                                             30  30 30 30 30 30   30  30                                     Compound symbol*.sup.3                                                                        P   Q  P  R  S  P    P  T                                       Properties of crosslinked                                                      rubber                                                                         Tensile strength, kg/cm.sup.2                                                                 204 197                                                                               202                                                                               223                                                                               216                                                                               153  117                                                                               191                                     Elongation, %  420 370                                                                               450                                                                               410                                                                               400                                                                               620  170                                                                               510                                     Hardness, JIS-A                                                                               71  70 69 72 68 67   82  70                                     Gasoline resistance (After immersion of 40°  C. × 48 hr in        Fuel C)                                                                        ΔV, %    +18 +29                                                                               +30                                                                               +29                                                                               +35                                                                               +133 +7 +32                                     Sour gasoline resistance (After immersion of 40 ° C. × 72 hr      × n cycles in                                                            Fuel C containing 2.5% of lauroyl peroxide)                                    n=3 (3 cycles) NC*.sup.4                                                                          NC NC NC NC Softened                                                                            NC Cracks appeared                         n=10 (10 cycles)                                                                              NC  NC NC NC NC Softened                                                                            NC Ruptured                                Sour gasohol resistance (After immersion of 40° × 72 hr           × n cycles in a                                                          solution consisting of 80 volume % of Fuel C containing 2.5% of lauroyl        peroxide and                                                                   20 volume % of methanol)                                                       n=3 (3 cycles) NC  NC NC NC NC Softened                                                                            NC Cracks appeared                         n=6 (6 cycles) NC  NC NC NC NC Softened                                                                            NC Ruptured                                n=10 (10 cycles)                                                                              NC  NC NC NC NC Softened                                                                            NC Ruptured                                Heat resistance (120 ° C. × 288 hr aging with air heating)         Change of tensile                                                                            +4  +6 +5 -3 -2 +12  -7 +5                                      strength, %                                                                    Change of elongation, %                                                                       -27 -11                                                                               -20                                                                               -15                                                                               -17                                                                               -16  -32                                                                               -68                                     Change of hardness, JIS-A                                                                     +6  +8 +8 +6 +7 +4   +8 +27                                     Ozone resistance, static (80 pphm, 40° C., 100% elongation)             24 hr              NC NC NC NC NC   NC C-3                                     Ozone resistance, dynamic (80 pphm, 40° C., 0 to 20% elongation)        24 hr              NC NC NC NC NC   NC A-1                                     288 hr             NC NC NC NC NC   NC Ruptured                                Low-temperature resistance:                                                                   -23 -19                                                                               -21                                                                               -25                                                                               -26                                                                               -14  -3 -22                                     Gehman torsion test T100, °C.                                           __________________________________________________________________________      *.sup.1 JSR N 220S, manufactured by Japan Synthetic Rubber Co., Ltd.           *.sup.2 Vinychlon 3000M, manufactured by Mitsui Toatsu Chemicals, Inc.         *.sup.3 Refer to Table 10.                                                     *.sup.4 No cracking                                                      

                                      TABLE 12                                     __________________________________________________________________________                                             Comparative                                                Example             Example                                                    48  49  50  51  52  32                                     __________________________________________________________________________     Multi-component copolymer rubber, parts                                                            90  80  70  60  40  100                                    PVC, parts          10  20  30  40  60  0                                      Zinc oxide          5.0 5.0 5.0 5.0 5.0 5.0                                    Stearic acid        1.0 1.0 1.0 1.0 1.0 1.0                                    SRF carbon black    70.0                                                                               60.0                                                                               50.0                                                                               40.0                                                                               20.0                                                                               80.0                                   DOP                 5.0 5.0 5.0 5.0 5.0 5.0                                    Accelerator TT      0.75                                                                               0.75                                                                               0.75                                                                               0.75                                                                               0.75                                                                               0.75                                   Sulfur              0.2 0.2 0.2 0.2 0.2 0.2                                    Properties of crosslinked rubber                                               Tensile strength, kg/cm.sup.2                                                                      189 201 217 220 195 126                                    Elongation, %       460 460 430 410 370 480                                    Hardness, JIS-A     68  70  71  72  74  69                                     Sour gasoline resistance (After immersion of 40° C. × 72 hr       × n cycles in Fuel C                                                     containing 2.5% of lauroyl peroxide)                                           n=3 (3 cycles)      NC  NC  NC  NC  NC  NC                                     n=10 (10 cycles)    NC  NC  NC  NC  NC  NC                                     Sour gasohol resistance (After immersion of 40° C. × 72 hr        × n cycles in a solution                                                 containing of 80 volume % of Fuel C containing 2.5% of                         lauroyl peroxide and 20 volume % of methanol)                                  n=3 (3 cycles)      NC  NC  NC  NC  NC  NC                                     n=6 (6 cycles)      NC  NC  NC  NC  NC  Softened                               n=10 (10 cycles)    NC  NC  NC  NC  NC  Softened                               Permanent compression set                                                                          37  41  43  46  57  28                                     (120° C. × 70 hr), %                                              __________________________________________________________________________

EXAMPLES 53 TO 56 AND COMPARATIVE EXAMPLES 33 TO 36

Multi-component copolymer rubber compositions (Examples 53 to 56) and multi-component copolymer rubbers (Comparative Examples 33 to 36) were compounded by a Banbury mixer with the formulations shown in Table 13. The compounds obtained were evaluated for processability from dischargability from Banbury mixer as well as from knitting performance, and good processability was indicated so o, and bad processability as X.

These compounds were press-cured under the conditions shown in Table 13. The vulcanized compounds were subjected to measurement of permanent compression set, heat resistance and gasoline resistance based on JIS K 6301 using the conditions shown in Table 14.

The results are shown in Table 14.

Comparison between the results of Examples 53 and 54 with the results of Comparative Examples 33 and 34 indicates that mixing of a conventional acrylic rubber [a multi-component copolymer rubber (I)] with a multi-component copolymer rubber of this invention overcomes the drawbacks of the conventional acrylic rubber, namely, processability, permanent compression set and gasoline resistance.

Comparison between the results of Examples 55 and 56 with the results of Comparative Examples 35 and 36 indicates that the drawback of a multi-component copolymer rubber of this invention, namely, heat resistance is improved by incorporating thereinto a conventional acrylic rubber [a multi-component copolymer rubber (I)].

                  TABLE 13                                                         ______________________________________                                                         A       B                                                      ______________________________________                                         Polymer           100       100                                                Zinc oxide         5                                                           Stearic acid       1         1                                                 HAF carbon black   50        50                                                Accelerator TT *  0.75                                                         Sulfur            0.2                                                          Ammonium benzoate            1                                                 Conditions for press-curing                                                                      170° C. ×                                                                   175° C. ×                                               20 min    20 min                                             ______________________________________                                          * tetramethylthiuram disulfide                                           

                                      TABLE 14                                     __________________________________________________________________________                 Example         Comparative Example                                            53  54  55  56  33  34  35  36                                     __________________________________________________________________________     Multi-component                                                                            (b) 10                                                                             (d) 20                                                                             (b) 80                                                                             (d) 70      (b) 100                                                                            (d) 100                                copolymer rubber of                                                            this invention                                                                 Multi-component                                                                            (a) 90                                                                             (c) 80                                                                             (a) 20                                                                             (c) 30                                                                             (a) 100                                                                            (c) 100                                        copolymer rubber (I)                                                           Compound formulation                                                                       A   B   A   B   A   B   A   B                                      Processability                                                                             o   o   o   o   x   x   o   o                                      Permanent compression                                                                      62  61  59  57  82  75  56  49                                     set, % (150° C. × 70 hr)                                          Heat resistance                                                                            -32 -29 -41 -38 -29 -25 -52 -49                                    (150° C. × 70 hr)                                                 Change of elongation, %                                                        Gasoline resistance (After immersion of 40° C. × 48 hr in         Fuel C)                                                                        ΔV, % 85  79  45  56  115 123 31  30                                     __________________________________________________________________________      (a) Ethyl acrylate/ethylidenenorbornene × 97/3 by weight                 (b) 2Cyanoethyl acrylate/nbutyl acrylate/ethylidenenorbornene ×          49/48/3 by weight                                                              (c) Ethyl acrylate/butyl acrylate/methoxyethyl acrylate/allyl glycidyl         ether × 40/30/27/3 by weight                                             (d) 2Cyanoethyl acrylate/nbutyl acrylate/allyl glycidyl ether ×          49/48/3 by weight                                                        

EXAMPLES 57 TO 61 AND COMPARATIVE EXAMPLES 37 TO 40

Each mixture having the formulation shown in Table 15 was kneaded by a Banbury mixer and an open roll and then press-cured at 170° C. for 20 min.

Each crosslinked rubber composition was subjected to measurement of characteristics in accordance with JIS K 6301.

The rubber composition was also subjected to measurement of sour gasoline resistance by the following method:

[Test Method for Sour Gasoline Resistance]

A sample was immersed at 70° C. for 24 hr in a solution obtained by dissolving 1 g of lauroyl peroxide in 99 g of Fuel C (a mixed solvent consisting of equal volumes of isooctane and toluene). This 1 cycle procedure was repeated 20 times (20 cycles). Then, the sample was dried at 100° C. for 15 hr under reduced pressure and subjected to measurement of tensile strength and elongation at break in accordance with JIS K 6301. The changes (%) from the value obtained before immersion were calculated and used as criteria of sour gasoline resistance.

The measurement results are shown in Table 16.

As is clear from Table 16, the composition of this invention gives a crosslinked product which is excellent in heat resistance, sour gasoline resistance, and ozone resistance, good in low-temperature resistance, tensile strength and elongation, and has a small permanent compression set.

                  TABLE 15                                                         ______________________________________                                                   Example     Comparative Example                                                57  58    59    60  61  37   38   39  40                             ______________________________________                                         Copolymer (A.sub.1)*.sup.1                                                                 75    50    75      75  15   90                                    Copolymer (A.sub.2)*.sup.2  75                                                 Copolymer (A.sub.3)*.sup.3                    75                               Copolymer (A.sub.4)*.sup.4                        75                           Copolymer (B.sub.1)*.sup.5                                                                 25    50        25      85        25  25                           Copolymer (B.sub.2)*.sup.6                                                                             25                                                     Copolymer (B.sub.3)*.sup.7               10                                    Copolymer (B.sub.4)*.sup.8      25                                             Zinc oxide  ← 5 →                                                  Stearic acid                                                                               ← 1 →                                                  HAF carbon black                                                                           ← 50 →                                                 Accelerator TT*.sup.9                                                                      ← 0.75 →                                               Sulfur      ← 0.2 →                                                ______________________________________                                          *.sup.1 A terpolymer produced by emulsion polymerization, consisting of        56% by weight of cyanoethyl acrylate, 41% by weight of butyl acrylate and      3% by weight of ethylidenenorbornene. Mooney viscosity ML.sub.1+4              (100° C.) = 56                                                          *.sup.2 A multicomponent copolymer produced by emulsion polymerization,        consisting of 26% by weight of cyanoethyl acrylate, 12% by weight of buty      acrylate, 53% by weight of ethyl acrylate, 3% by weight of                     ethylidenenorbornene and 6% by weight of methoxyethyl acrylate. Mooney         viscosity ML.sub.1+4 (100° C.) = 42                                     *.sup.3 A terpolymer produced by emulsion polymerization, consisting of        73% by weight of cyanoethyl acrylate, 24% by weight of butyl acrylate and      3% by weight of ethylidenenorbornene. Mooney viscosity ML.sub.1+4              (100° C.) = 60                                                          *.sup.4 A terpolymer produced by emulsion polymerization, consisting of        14% by weight of cyanoethyl acrylate, 83% by weight of butyl acrylate and      3% by weight of ethylidenenorbornene. Mooney viscosity ML.sub.1+4              (100° C.) = 49                                                          *.sup.5 A terpolymer produced by emulsion polymerization, consisting of        25% by weight of acrylonitrile, 40% by weight of butadiene and 35% by          weight of butyl acrylate. Mooney viscosity ML.sub.1+4 (100° C.) =       70                                                                             *.sup.6 A copolymer produced by emulsion polymerization, consisting of 35      by weight of acrylonitrile and 65% by weight of butadiene. Mooney              viscosity ML.sub.1+4 (100° C.) = 56                                     *.sup.7 A copolymer produced by emulsion polymerization, consisting of 35      by weight of acrylonitrile and 65% by weight of butadiene. A liquid rubbe      whose [η]as measured at 30° C. in tetrahydrofuran is 0.05.          *.sup.8 A terpolymer produced by emulsion polymerization, consisting of        30% by weight of acrylonitrile, 65% by weight of butadiene and 5% by           weight of methacrylic acid. Mooney viscosity ML.sub.1+4 (100° C.)       60                                                                             *.sup.9 Tetramethylthiuram disulfide                                     

                                      TABLE 16                                     __________________________________________________________________________                         Example        Comparative Example                                             57 58 59 60 61 37 38 39 40                                 __________________________________________________________________________     Tensile strength, kg/cm.sup.2                                                                      145                                                                               151                                                                               162                                                                               131                                                                               162                                                                               175                                                                               105                                                                               112                                                                               124                                Elongation, %       360                                                                               370                                                                               420                                                                               430                                                                               370                                                                               380                                                                               480                                                                               220                                                                               450                                Hardness, JIS-A     72 70 72 69 71 69 68 78 68                                 Gasoline resistance (After immersion of                                                            +35                                                                               +45                                                                               +31                                                                               +42                                                                               +33                                                                               +54                                                                               +21                                                                               +11                                                                               +58                                40° C. × 48 hr in Fuel C) ΔV, %                             Sour gasoline resistance (After immersion                                      of 70° C. × 24 hr × 20 cycles in Fuel C                     containing 1% of lauroyl peroxide)                                             Change of tensile strength, %                                                                      -24                                                                               -41                                                                               -40                                                                               -44                                                                               -40                                                                               -72                                                                               -52                                                                               -18                                                                               -84                                Change of elongation, %                                                                            -28                                                                               -45                                                                               -41                                                                               -38                                                                               -38                                                                               -83                                                                               -22                                                                               -25                                                                               -10                                Heat resistance (150°  C. × 12 hr aging                           with air heating)                                                              Change of tensile strength, %                                                                      +3 -2 +7 +2 +5 -65                                                                               -54                                                                               -21                                                                               +6                                 Change of elongation, %                                                                            -31                                                                               -41                                                                               -45                                                                               -49                                                                               -42                                                                               -92                                                                               -88                                                                               -64                                                                               -32                                Change of hardness, JIS-A                                                                          +12                                                                               +17                                                                               +15                                                                               +15                                                                               +13                                                                               +21                                                                               +7 +18                                                                               +11                                Ozone resistance (50 pphm, 40° C.,                                                          ← No cracking for 96 hr →                      30% elongation)                                                                Low-temperature resistance, Gehman                                                                 -22                                                                               -25                                                                               -24                                                                               -23                                                                               -23                                                                               -26                                                                               -28                                                                               -7 -19                                torsion test                                                                   T100, °C.                                                               Permanent compression set, 150° C. × 70 hr                                            25 32 31 59 38 61 29 53 33                                 __________________________________________________________________________

EXAMPLES 62 TO 65 AND COMPARATIVE EXAMPLE 41

Test methods used in these Examples were as follows:

Preparation of Kneaded Compounds

Unvulcanized rubber compounds were kneaded by a rubber test roll mill (6-inch and 14-inch rolls) to obtain sheet-like kneaded compounds each having a thickness of 8 mm, a width of 50 mm and a length of 80 mm and having a smooth surface.

Adhesion by Vulcanization

A sheet-like kneaded compound of the multi-component copolymer rubber of this invention and another sheet-like kneaded compound of a different rubber both obtained above were superimposed and inserted into a compression type mold, where they were subjected to vulcanization at 170° C. for 15 min at a surface pressure of 2 kg/cm² applied by an electrically heated press whereby a sheet-like laminate was produced.

Measurement of Bonding Strength

The laminate obtained above was cut into a ribbon-like sample of 2.5 mm in width and the sample was subjected to 90° peeling test in accordance with the peeling test specified by item 7 of JIS K 6801, whereby the bonding strength of the laminate was measured. The results are shown in Table 17.

Measurement of Sour Gasoline Resistance

A test specimen was immersed at 40° C. for 72 hr in a solution obtained by dissolving 2.5 g of lauroyl peroxide in 97.5 g of Fuel C (a mixed solvent consisting of equal volumes of isooctane and toluene), in such a way that the multi-component copolymer rubber of the laminate came in contact with the solution. This 1 cycle procedure was repeated twice (2 cycles). Then, the specimen was taken out of the solution, dried at 100° C. for 15 hr under reduced pressure and bent at an angle of 180° to observe the formation of cracks. The results are shown in Table 17.

The unvulcanized rubber compounds used in the above preparation of kneaded compounds had the following formulations, in which unless otherwise specified, parts are by weight:

    ______________________________________                                         [Formulations of multi-component copolymer rubber compounds]                   Polymer (a) or (b)                                                                              100         parts                                             Steatric acid    1                                                             HAF black        50                                                            Peroximon F40    0.2                                                           Ca(OH).sub.2     10                                                             Note:                                                                          (a) 2Cyanoethylacrylate/ethyl acrylate/nbutyl                                  acrylate/ethylidenenorbornene = 37/30/30/3 by weight                           (b) 2Cyanoethyl acrylate/ethyl acrylate/2ethylhexyl                            acrylate/dicyclopentadiene = 25/40/32/3 by weight                             [Formulations of other rubber compounds]                                       NBR:       Polymer*.sup.1                                                                               100       parts                                                  Stearic acid  1                                                                ZnO           5                                                                SRF           50                                                               Ca(OH).sub.2  10                                                               Epoxy resin*.sup.2                                                                           5                                                                Maleic anhydride                                                                             0.3                                                              2-Methylimidazole                                                                            1.0                                                              Sulfur        0.3                                                              CZ            2                                                                TET           1.5                                                              TS            1                                                     FKM:       Polymer*.sup.3                                                                               100       parts                                                  CMP #2*.sup.4 1.85                                                             CMB #3*.sup.4 2.6                                                              MgO           3                                                                Ca(OH).sub.2  6                                                                MT black      20                                                     Note:                                                                          *.sup.1 N 220S, manufactured by Japan Synthetic Rubber Co., Ltd.               *.sup.2 Epicoat #828, manufactured by Shell                                    *.sup.3 E45, manufactured by Du pont                                           *.sup.4 Vulcanization accelerator, manufactured by Du Pont, #20 is a           polycyclic quaternary phosphate and #30 is an aromatic salt.                  CZ:        N--cyclohexylbenzothiazyl sulfenamide                               TET:       Tetraethylthiuram disulfide                                         TS:        Tetramethylthiuram 25                                               CR:        Neoprene WRT*.sup.5                                                                          100    parts                                                     Stearic acid  0.5                                                              SRF black     60                                                               Hydrous silicic                                                                              20                                                               acid                                                                           Aromatic oil  15                                                               ZnO           5                                                                Accelerator 22                                                                               0.5                                                   ______________________________________                                          Note:                                                                          *.sup.5 A polychloroprene rubber, manufactured by Du Pont.               

As seen from Examples 62 to 65, laminates between the multi-component copolymer rubber of this invention and a commercially available rubber have a strong bonding strength between the two rubbers as a result of vulcanization. (The two rubbers may be allowed to adhere to each other by the use of an adhesive).

Comparison of Example 62 with Comparative Example 41 indicates that a laminate of a multi-component copolymer rubber of this invention and an NBR has a strikingly improved sour gasoline resistance over the NBR.

                                      TABLE 17                                     __________________________________________________________________________              Example                                                                        62    63    64    65                                                           Multi-                                                                               Multi-                                                                               Multi-                                                                               Multi-                                                       component                                                                            component                                                                            component                                                                            component                                                                            Comparative                                            copolymer                                                                            copolymer                                                                            copolymer                                                                            copolymer                                                                            Example                                                rubber                                                                               rubber                                                                               rubber                                                                               rubber                                                                               41                                                     (a)/NBR                                                                              (a)/FKM                                                                              (a)/CR                                                                               (b)/NBR                                                                              NBR                                           __________________________________________________________________________     Bonding strength                                                                        2.1   2.0   2.5   2.3   --                                            (peeling strength                                                              of laminate),                                                                  kg/cm.sup.2                                                                    Sour gasoline                                                                           NC*.sup.2                                                                            NC*.sup.2                                                                            NC*.sup.2                                                                            NC*.sup.2                                                                            Cracks                                        resistance *.sup.1               appeared.                                     __________________________________________________________________________      *.sup.1 After immersion of 40° C. × 72 hr × 2 cycles i      Fuel C containing 2.5% of lauroyl peroxide.                                    *.sup.2 No cracking                                                      

EXAMPLES 66 TO 72 AND COMPARATIVE EXAMPLE 42

Each sample of multi-component copolymer rubbers (Examples 66 to 72) and a butadiene-acrylonitrile rubber (NBR) (Comparative Example 42) shown in the upper section of Table 19 was subjected to compounding by a Banbury mixer in accordance with the formulation shown in Table 18. Each compound obtained was press-cured under the conditions shown in the bottom section of Table 18.

The crosslinked rubber compounds obtained were subjected to measurement of characteristics in accordance with JIS K 6301. The results are shown in Table 19.

The crosslinked rubber compounds were also subjected to measurement of sour gasoline resistance by the following method. The results are shown in Table 19.

[Text Method for Sour Gasoline Resistance]

A test specimen was immersed at 40° C. for 72 hr in a solution obtained by dissolving 2.5 g of lauroyl peroxide in 97.5 g of Fuel C (a mixed solvent consisting of equal volumes of isooctane and toluene). This 1 cycle procedure was repeated n times (n cycles). After each cycle, the specimen was taken out, dried at 100° C. for 15 hr under reduced pressure and bent at an angle of 180° to observe the formation of cracks.

As appreciated from Table 19, the rubber compounds of this invention are excellent in sour gasoline resistance, heat resistance and ozone resistance and good in permanent compression set and balance between gasoline resistance and low-temperature resistance. Therefore, they provide a very superior material for inner tubes of fuel rubber hoses.

                                      TABLE 18                                     __________________________________________________________________________                  Compound symbol                                                                A     B     C     D     E                                         __________________________________________________________________________     Compound formulation                                                           Polymer      100.0 100.0 100.0 100.0 100.0                                     Zinc oxide   5.0                     5.0                                       Stearic acid 1.0   1.0   1.0   1.0   1.0                                       HAF carbon black*.sup.0                                                                     50.0  50.0  50.0  50.0                                            DOP*.sup.2                           5.0                                       Accelerator TT*.sup.3                                                                       0.75                    1.5                                       Accelerator CZ*.sup.4                2.0                                       Accelerator TRA*.sup.5         0.5                                             Accelerator EUR*.sup.6         1.0                                             Sulfur       0.2                     0.5                                       Peroximon F40*.sup.7                                                                              2.0                                                         Ammonium benzoate        1.0                                                   Potassium stearate             3.0                                             SRF carbon black*.sup.1              60.0                                      Conditions for press-curing                                                                 170° C. ×                                                               180° C. ×                                                               175° C. ×                                                               175° C. ×                                                               160° C. ×                                 20 min                                                                               20 min                                                                               20 min                                                                               20 min                                                                               20 min                                    __________________________________________________________________________      *.sup.0 High abrasion furnace black                                            *.sup.1 Semi-reinforcing furnace black                                         *.sup.2 Dioctyl phthalate                                                      *.sup.3 Tetramethylthiuram disulfide                                           *.sup.4 N-- cyclohexyl-2-benzothiazolesulfenamide                              *.sup.5 Dipentamethylenethiuram hexasulfide                                    *.sup.6 1,3-Diethylthiourea                                                    *.sup.7 1,3-Bis(t-butylperoxyisopropyl)benzene                           

                                      TABLE 19                                     __________________________________________________________________________                                            Comparative                                              Example               Example                                                  66 67 68 69 70 71 72  42                                      __________________________________________________________________________     Multi-component copolymer                                                      rubber composition,                                                            Component (A)                                                                  2-Cyanoethyl acrylate                                                                           49 37 26 35    83 12  NBR*.sup.1                              4-Cyanobutyl acrylate        44                                                Component (B)                                                                  Ethyl acrylate      30 52 31 54                                                n-Butyl acrylate 48 30 14 31    14 85                                          Component (C)                                                                  Ethylidene norbornene                                                                           3  3  3        3  3                                           Allyl glycidyl ether   3                                                       Vinyl chloroacetate          2                                                 Component (D)                                                                  Methoxyethyl acrylate  5                                                       Compound symbol*.sup.2                                                                          A  B  A  C  D  A  A   A                                       Properties of crosslinked                                                      rubber                                                                         Tensile strength, kg/cm.sup.2                                                                   131                                                                               136                                                                               129                                                                               154                                                                               142                                                                               83 132 197                                     Elongation, %    480                                                                               410                                                                               500                                                                               380                                                                               530                                                                               160                                                                               520 490                                     Hardness, JIS-A  72 71 69 67 65 84 66  72                                      Gasoline resistance (After immersion of 40° C. × 48 hr in         Fuel C)                                                                        ΔV, %      +31                                                                               +35                                                                               +38                                                                               +39                                                                               +41                                                                               +4 +70 +40                                     Sour gasoline resistance (After immersion of 40° C. × 72 hr       × n cycles in                                                            Fuel C containing 2.5% of lauroyl peroxide)                                    n=2 (2 cycles)   NC*.sup.3                                                                         NC NC NC NC NC NC  Cracks                                                                         appeared                                n=4 (4 cycles)   NC NC NC NC NC NC Softened                                                                           Ruptured                                n=8 (8 cycles)   NC NC NC NC NC NC Softened                                                                           Ruptured                                Heat resistance (150° C. × 72 hr aging with air heating)          Change of tensile                                                                               -8 ±0                                                                             -11                                                                               +4 -9 -11                                                                               +2  -82                                     Strength, %                                                                    Change of elongation, %                                                                         -51                                                                               -26                                                                               -38                                                                               -32                                                                               -37                                                                               -57                                                                               -29 -100                                                                           (No elonga-                                                                    tion)                                   Change of hardness, JIS-A                                                                       +13                                                                               +9 +12                                                                               +13                                                                               +14                                                                               +14                                                                               +10 +25                                     Ozone resistance (50 pphm, 40° C.,                                                       ← No cracking for 168 hr →                                                               Cracks                                  30% elongation)                        appeared                                                                       in 2 hr.                                Low-temperature resistance:                                                                     -24                                                                               -21                                                                               -21                                                                               -25                                                                               -28                                                                               -2 -13 -21                                     Gehman torsion test T100, °C.                                           Permanent compression set,                                                                      51 23 56 47 54 63 61  66                                      (150° C. × 70 hr), %                                              __________________________________________________________________________      *.sup.1 JSR N220S, manufactured by Japan Synthetic Rubber Co., Ltd.            *.sup.2 Refer to Table 18.                                                     *.sup.3 No cracking                                                       

What is claimed is:
 1. A multi-component copolymer rubber composition consisting essentially of a multi-component copolymer rubber, consisting essentially of:(A) 10 to 69.5% by weight of a cyano-substituted alkyl (meth)acrylate of the formula: ##STR9## wherein R¹ is hydrogen or methyl and --R² --CN is a cyanoalkyl group of 2 to 12 carbon atoms, (B) 30 to 89.5% by weight of an alkyl acrylate, (C) 0.5 to 10% by weight of a cross-linkable monomer, and (D) 0 to 10% by weight of another ethylenically unsaturated monomer copolymerizable with the components (A), (B) and (C), and a vinyl chloride resin.
 2. The multi-component copolymer rubber composition according to claim 1, wherein the multi-component copolymer rubber consists essentially of(A) 20 to 69.5% by weight of said cyano-substituted alkyl (meth)acrylate, (B) 30 to 79.5% by weight of an alkyl acrylate, (C) 0.5 to 10% by weight of a crosslinkable monomer, (D) 0 to 10% by weight of another ethylenically unsaturated monomer copolymerizable with (A), (B) and (C).
 3. A multi-component copolymer rubber composition consisting essentially of a multi-component copolymer rubber, consisting essentially of:(A) 10 to 69.5% by weight of a cyano-substituted alkyl (meth)acrylate of the formula: ##STR10## wherein R¹ is hydrogen or methyl and --R² --CN is a cyanoalkyl group of 2 to 12 carbon atoms, (B) 30 to 89.5% by weight of an alkyl acrylate, (C) 0.5 to 10% by weight of a cross-linkable monomer, and (D) 0 to 10% by weight of another ethylenically unsaturated monomer copolymerizable with (A), (B), and (C); and a vinylidene fluoride polymer.
 4. The multi-component copolymer rubber composition according to claim 3, wherein the multi-component copolymer rubber consists essentially of(A) 20 to 69.5% by weight of said cyano-substituted alkyl (meth)acrylate, (B) 30 to 79.5% by weight of an alkyl acrylate, (C) 0.5 to 10% by weight of a crosslinkable monomer, and (D) 0 to 10% by weight of another ethylenically unsaturated monomer copolymerzable with (A), (B) and (C).
 5. A multi-component copolymer rubber composition consisting essentially of a multi-component copolymer rubber, consisting essentially of:(A) 10 to 69.5% by weight of a cyano-substituted alkyl (meth)acrylate of the formula: ##STR11## wherein R¹ is hydrogen or methyl and --R² --CN is a cyanoalkyl group of 2 to 12 carbon atoms, (B) 30 to 89.5% by weight of an alkylacrylate, (C) 0.5 to 10% by weight of a crosslinkable monomer, and (D) 0 to 10% by weight of an another ethylenically unsaturated monomer copolymerizable with (A), (B) and (C), and a nitrile rubber.
 6. The multi-component copolymer rubber composition according to claim 5, wherein the multi-component copolymer rubber consists essentially of(A) 20 to 69.5% by weight of said cyano-substituted alkyl (meth)acrylate, (B) 30 to 79.5% by weight of an alkyl acrylate, (C) 0.5 to 10% by weight of a crosslinkable monomer, and (D) 0 to 10% by weight of another ethylenically unsaturated monomer copolymerizable with (A), (B) and (C).
 7. The multi-component copolymer rubber composition according to claim 6, wherein the nitrile rubber is a copolymer or a hydrogenated product thereof, the copolymer consisting essentially of 20 to 90% by weight of a conjugated diene, 10 to 55% by weight of an α,β-unsaturated nitrile, 0 to 70% by weight of an α,β-unsaturated carboxylic acid ester and 0 to 20% by weight of a monomer containing a carboxyl, epoxy, hydroxyl or amino group.
 8. A multi-component copolymer rubber composition, consisting essentially of;(i) a multi-component copolymer rubber, consisting essentially of:(A) 10 to 69.5% by weight of a cyano-substituted alkyl (meth)acrylate of the formula: ##STR12## wherein R¹ is hydrogen or methyl and --R² --CN is a cyanoalkyl group of 2 to 12 carbon atoms, (B) 30 to 89.5% by weight of an alkyl acrylate, (C) 0.5 to 10% by weight of a cross-linkable monomer, and (D) 0 to 10% by weight of another ethylenically unsaturated monomer copolymerizable with (A), (B), and (C), and (ii) an acrylic rubber which is a multi-component copolymer rubber consisting of:(A') 99.5 to 39.5% by weight of an alkylacrylate, (B') 0 to 60% by weight of an alkoxyalkyl acrylate, (C') 0.5 to 10% by weight of at least one compound selected from the group consisting of diene compounds, (meth)acrylic acid esters containing a dihydrodicyclopentadienyl group, epoxy group-containing ethylenically unsaturated compounds and active halogen-containing ethylenically unsaturated compounds, and (D') 0 to 10% by weight of another ethylenically unsaturated compound copolymerizable with (A'), (B') and (C').
 9. The multi-component copolymer rubber composition according to claim 8, wherein the multi-component copolymer rubber consists essentially of(A) 20 to 69.5% by weight of said cyano-substituted alkyl (meth)acrylate, (B) 30 to 79.5% by weight of an alkyl acrylate, (C) 0.5 to 10% by weight of a crosslinkable monomer, and (D) 0 to 10% by weight of another ethylenically unsaturated monomer copolymerizable with (A), (B) and (C). 